Anti-ICOS agonist antibodies and uses thereof

ABSTRACT

The present invention provides isolated monoclonal antibodies (e.g., humanized and human monoclonal antibodies) that bind to human Inducible T Cell COStimulator (ICOS) and exhibit therapeutically desirable functional properties, e.g., the ability to stimulate human ICOS activity. Nucleic acid molecules encoding the antibodies of the invention, expression vectors, host cells, and methods for expressing the antibodies of the invention are also provided. Immunoconjugates, bispecific molecules, and pharmaceutical compositions comprising the antibodies of the invention are also provided. The antibodies of the invention can be used, for example, as an agonist to stimulate or enhance an immune response in a subject, e.g., antigen-specific T cell responses against a tumor or viral antigen. The antibodies of the invention can also be used in combination with other antibodies (e.g., PD-1, PD-L1, and/or CTLA-4 antibodies) to treat, for example, cancer. Accordingly, the antibodies can be used in therapeutic applications and methods to detect ICOS protein.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/946,625, filed on Apr. 5, 2018, which claims the benefit of priorityof U.S. Provisional Application Nos. 62/483,158 (filed on Apr. 7, 2017),62/514,151 (filed on Jun. 2, 2017), 62/545,732 (filed on Aug. 15, 2017)and 62/581,412 (filed on Nov. 3, 2017). The contents of theaforementioned applications are hereby incorporated by reference intheir entireties.

TECHNICAL FIELD

This invention relates to anti-Inducible T Cell COStimulator (ICOS)agonist antibodies and pharmaceutical compositions thereof, and methodsfor using such antibodies, e.g., for treating cancer by administeringthe anti-ICOS agonist antibodies and pharmaceutical compositions.

SEQUENCE LISTING

The instant application contains a Sequence Listing which has been filedelectronically in ASCII format and is hereby incorporated by referencein its entirety. Said ASCII copy, created on Mar. 13, 2019, is namedMXI-556DV3_Sequence_Listing.txt and is 318,969 bytes in size.

BACKGROUND

A need exists to combat the global epidemic of cancer. Cancer is one ofthe leading causes of disease and the second leading cause of deathworldwide. Cancer accounted for 8.8 million deaths in 2015. Globally,nearly one in six deaths is due to cancer. In 2018, there will be anestimated 1,735,350 new cancer cases diagnosed and 609,640 cancer deathsin the United States. In 2012, there were an estimated 3.5 million newcancer cases and 1.9 million cancer deaths in Europe. The World HealthOrganization estimates in 2018 that the number of new cases of cancer isexpected to rise by about 70% over the next two decades.

Traditional cancer treatments include surgery, radiation therapy, andchemotherapy, amongst other therapies. In recent years, immuno-oncologyhas emerged as a new option to treat cancer. Immuno-oncology isdifferent from traditional cancer treatments, which, for example, hastried to target tumors directly or to disrupt the tumor blood supply.Instead, immuno-oncology is designed to use the patient's own immuneresponse to treat cancer. Understanding how the immune system affectscancer development and how it can be used to treat cancer has been achallenging, complicated problem. For example, patients may not respondto certain immuno-oncology drugs, and some develop resistancemechanisms, such as T cell exhaustion, which is when a T cell, aspecific type of white blood cell, no longer functions properly. (Dempkeet al., Eur. J. of Cancer, 74 55-72 (2017)).

An important role of the immune system is its ability to differentiatebetween normal cells and “foreign” cells. The immune system can thusattack the foreign cells and leave normal cells alone. To do this, theimmune system uses “checkpoints,” which are molecules on certain immunecells that need to be activated or inactivated to begin an immuneresponse. Tumor cells can sometimes use these checkpoints to avoid beingattacked by the immune system. Some immuno-oncology drugs target thesecheckpoints by acting as checkpoint inhibitors. Programmed death protein1 (PD-1) is a checkpoint inhibitor that typically acts as a brake toprevent T cells from attacking other cells in the body. PD-1 does thiswhen it binds to programmed death ligand 1 (PD-L1), a protein on somenormal (and cancer) cells. When PD-1 binds to PD-L1, this interactiontells the T cell to not attack other cells. Some cancer cells have largeamounts of PD-L1, which helps them evade immune attack. Therapeuticagents such as monoclonal antibodies that target this PD-1/PD-L1interaction, such as nivolumab (Opdivo®), can block the PD-1/PD-L1binding to increase the body's immune response against tumor cells.

A need exists for drugs that target different mechanisms of action thatwork either alone or in combination with checkpoint inhibitors to safelyand effectively treat cancer and other diseases or conditions. T cellactivation and function are regulated by the innate immune systemthrough costimulatory molecules in the CD28-superfamily (e.g., positiveand negative costimulatory molecules that promote or inhibit activationof the T cell receptor signal, respectively). Inducible COStimulatormolecule (ICOS), also known as CD278, is an immune checkpoint proteinthat is a member of this CD28-superfamily. ICOS is a 55-60 kDa type Itransmembrane protein that is expressed on T cells after T cellactivation and costimulates T-cell activation after binding its ligand,ICOS-L (B7H2). ICOS is expressed by CD4+ cells, CD8+ cells, andregulatory T cells (Treg). ICOS also has been shown to be a key playerin the function of follicular helper T cells (Tfhs) and the humoralimmune response.

The magnitude and quality of a T cell's immune response depends in parton the complicated balance between co-stimulatory and inhibitory signalsto the T cell. To improve patients' response rates after immunotherapyand to overcome drug resistance, a need exists for novel immuno-oncologytherapies.

SUMMARY OF THE INVENTION

The present invention provides isolated monoclonal antibodies (e.g.,humanized and human monoclonal antibodies) that bind to human ICOS (SEQID NO: 1), i.e., anti-huICOS antibodies, and exhibit therapeuticallydesirable functional properties. The antibodies of the invention can beused as an agonist to stimulate or enhance an immune response in asubject, e.g., to stimulate human ICOS activity and/or to provideantigen-specific T cell responses against a tumor or viral antigen. Theantibodies of the invention can also be used in combination with otherantibodies (e.g., PD-1, PD-L1, and/or CTLA-4 antibodies) to treatvarious conditions, for example, cancer. Accordingly, the antibodiesdisclosed herein, either alone or in combination with other agents, canbe used to treat various conditions or diseases, including cancer. Inother embodiments, the antibodies disclosed herein can be used inmethods to detect ICOS protein.

In one aspect, the isolated antibody is a humanized isolated antibody(or antigen binding portion thereof) that binds to human ICOS and blocksthe binding and/or the interaction of an ICOS ligand (e.g., humanICOS-L) to human ICOS and

(a) induces proliferation and interferon-gamma (IFN-γ) production inCD25− CD4+ T cells with an EC50 of about 0.01 to about 0.16 nM in an invitro CHO-OKT3-CD32A co-culture assay; and/or

(b) induces IFN-γ production in CD25− CD4+ T cells with an EC50 of about0.002 nM to about 0.4 nM in a staphylococcal enterotoxin B in a CD25−CD4+ T cell and B cell co-culture assay.

In another embodiment, the antibody (or antigen binding portion thereof)exhibits one or more of the following features:

(a) binds to human T cells with an EC50 of about 0.7 nM and cynomolgus Tcells with an EC50 of about 0.3 nM;

(b) binds to human activated CD4+ T cells;

(c) does not bind to human CD28 or human CTLA-4;

(d) activates at least one primary T lymphocyte, such as a CD4+ effectorT (Teff) cell, a follicular helper T (Tfh) cell, and a regulatory T(Treg) cell;

(e) induces phosphorylation of protein kinase B (pAkt) in an in vitroprimary T cell signaling assay with an EC50 of about 30 nM;

(f) induces interleukin-10 (IL-10) production in response tostaphylococcal enterotoxin B in a Tfh and naive B cell co-culture assay;

(g) induces a greater proliferation increase of CD3-stimulated Teffscompared to CD45RA+ Tregs and CD45RO+ Tregs in an in vitro assay;

(h) reduces Teff suppression by Tregs;

(i) does not increase cytokine production in a whole blood cell assay at10 μg/mL;

(j) increases secretion of at least one of IL-10 and IFN-g by Tfh cellsin vitro;

(k) stimulates ICOS-mediated signaling;

(l) has increased affinity for CD32B and/or CD32A; and/or

(m) has decreased affinity for CD16.

In another embodiment, the isolated antibody is a humanized isolatedantibody (or antigen binding portion thereof) that binds to human ICOSand blocks the binding and/or the interaction of an ICOS ligand (e.g.,human ICOS-L) to human ICOS and induces proliferation andinterferon-gamma (IFN-γ) production in CD25− CD4+ T cells with an EC50of about 0.083 nM in an in vitro CHO-OKT3-CD32A co-culture assay. Inanother embodiment, the isolated antibody is a humanized isolatedantibody (or antigen binding portion thereof) that binds to human ICOSand blocks the binding and/or the interaction of an ICOS ligand (e.g.,human ICOS-L) to human ICOS and induces proliferation andinterferon-gamma (IFN-γ) production in CD25− CD4+ T cells with an EC50of about 0.01 to about 0.1 nM in an in vitro CHO-OKT3-CD32A co-cultureassay.

In one aspect, the isolated antibody is a humanized isolated antibody(or antigen binding portion thereof) that binds to human ICOS and blocksthe binding and/or the interaction of an ICOS ligand (e.g., humanICOS-L) to human ICOS and induces IFN-γ production in CD25− CD4+ T cellswith an EC50 of about 0.2 nM in a staphylococcal enterotoxin B in aCD25− CD4+ T cell and B cell co-culture assay. In another aspect, theisolated antibody is a humanized isolated antibody (or antigen bindingportion thereof) that binds to human ICOS and blocks the binding and/orthe interaction of an ICOS ligand (e.g., human ICOS-L) to human ICOS andinduces IFN-γ production in CD25− CD4+ T cells with an EC50 of about0.01-0.1 nM in a staphylococcal enterotoxin B in a CD25− CD4+ T cell andB cell co-culture assay.

In another embodiment, the antibody (or antigen binding portion thereof)binds to human, cynomolgus, mouse, and rat ICOS.

In another aspect, the isolated antibody binds to human InducibleCOStimulator molecule (ICOS) and comprises:

(a) a heavy chain variable domain comprising CDR1, CDR2, and CDR3regions comprising the amino acid sequences of SEQ ID NOs: 9, 10 and 11,respectively, and a light chain variable domain comprising CDR1, CDR2,and CDR3 regions comprising the amino acid sequences of SEQ ID NOs: 12,14 and 15, respectively;

(b) a heavy chain variable domain comprising CDR1, CDR2, and CDR3regions comprising the amino acid sequences of SEQ ID NOs: 18, 19 and20, respectively, and a light chain variable domain comprising CDR1,CDR2, and CDR3 regions comprising the amino acid sequences of SEQ IDNOs: 21, 22 and 23, respectively;

(c) a heavy chain variable domain comprising CDR1, CDR2, and CDR3regions comprising the amino acid sequences of SEQ ID NOs: 26, 27 and28, respectively, and a light chain variable domain comprising CDR1,CDR2, and CDR3 regions comprising the amino acid sequences of SEQ IDNOs: 29, 30 and 31, respectively;

(d) a heavy chain variable domain comprising CDR1, CDR2, and CDR3regions comprising the amino acid sequences of SEQ ID NOs: 34, 35 and36, respectively, and a light chain variable domain comprising CDR1,CDR2, and CDR3 regions comprising the amino acid sequences of SEQ IDNOs: 37, 38 and 39, respectively;

(e) a heavy chain variable domain comprising CDR1, CDR2, and CDR3regions comprising the amino acid sequences of SEQ ID NOs: 42, 43, and44, respectively, and a light chain variable domain comprising CDR1,CDR2, and CDR3 regions comprising the amino acid sequences of SEQ IDNOs: 45, 46, and 47, respectively;

(f) a heavy chain variable domain comprising CDR1, CDR2, and CDR3regions comprising the amino acid sequences of SEQ ID NOs: 42, 43, and44, respectively, and a light chain variable domain comprising CDR1,CDR2, and CDR3 regions comprising the amino acid sequences of SEQ IDNOs: 49, 50, and 51, respectively; or

(g) a heavy chain variable domain comprising CDR1, CDR2, and CDR3regions comprising the amino acid sequences of SEQ ID NOs: 191, 192, and193, respectively, and a light chain variable domain comprising CDR1,CDR2, and CDR3 regions comprising the amino acid sequences of SEQ IDNOs: 194, 195, and 196, respectively.

In another aspect, the isolated antibody binds to human InducibleCOStimulator molecule (ICOS), and the heavy and light chain variableregions comprise:

(a) the amino acid sequences of SEQ ID NOs: 5 and 6, respectively;

(b) the amino acid sequences of SEQ ID NOs: 16 and 17, respectively;

(c) the amino acid sequences of SEQ ID NOs: 24 and 25, respectively;

(d) the amino acid sequences of SEQ ID NOs: 32 and 33, respectively;

(e) the amino acid sequences of SEQ ID NOs: 40 and 41, respectively;

(f) the amino acid sequences of SEQ ID NOs: 40 and 48, respectively; or

(g) the amino acid sequences of SEQ ID NOs: 186 and 189, respectively.

In another aspect, the isolated, full-length, humanized monoclonalantibody that binds to human Inducible COStimulator molecule (ICOS)comprises heavy chains that comprise the amino acid sequence set forthin SEQ ID NO: 7 and light chains that comprise the amino acid sequenceset forth in SEQ ID NO: 8.

In one embodiment, the isolated antibody competes for binding to ICOSwith or binds to the same epitope as an antibody that blocks theinteraction of human ICOS and human ICOS-L. In another embodiment, theisolated antibody specifically binds to one or more residues ofSIFDPPPFKVTL (SEQ ID NO: 203) of human ICOS. In another embodiment, theICOS epitope comprises amino acid residues SIFDPPPFKVTL (SEQ ID NO: 203)of human ICOS.

In one embodiment, the antibodies of the invention are full-lengthantibodies, for example, of an IgG1, IgG2, IgG2a, or IgG4 isotype. Inanother embodiment, the antibodies are binding fragments, such as Fab,Fab′ or (Fab′)2 fragments, or single chain antibodies.

In one aspect, the anti-ICOS antibodies, or antigen binding portionsthereof, bind to Fc receptors, such as one or more activating Fc gammareceptors (FcγRs). In certain embodiments, the antibody comprises atleast one amino acid substitution in the Fc region compared to humanIgG1 sequence (SEQ ID NO: 206), which enhances affinity of the antibodyto an FcγR, e.g., FcγRIIb, such as one or more amino acid substitutionat a position comprising at least one of 234, 235, 236, 237, 239, 266,267, 268, 325, 326, 327, 328, and/or 332, according to the EU index,e.g., 234D, 234E, 234F, 234W, 235D, 235F, 235R, 235Y, 236D, 236N, 237D,237N, 239D, 239E, 266M, 267D, 267E, 268D, 268E, 327D, 327E, 328F, 328W,328Y, and/or 332E. In other embodiments, the Fc region comprises atleast two substitutions of 235Y-267E, 236D-267E, 239D-268D, 239D-267E,267E-268D, 267E-268E, and/or 267E-328F compared to human IgG1 sequence(SEQ ID NO: 206). In yet another embodiment, the amino acid substitutionin the Fc region is S267E compared to human IgG1 sequence as set forthin SEQ ID NO: 206.

In another aspect, the invention provides immunoconjugates comprising anantibody of the invention, or antigen-binding portion thereof, linked toa therapeutic agent, e.g., a cytotoxic agent or a radioactive isotope,as well as a bispecific molecules comprising an antibody, orantigen-binding portion thereof, of the invention, linked to a secondfunctional moiety having a different binding specificity than saidantibody, or antigen binding portion thereof.

Compositions (e.g., pharmaceutical compositions) comprising an antibody,or antigen-binding portion thereof, or immunoconjugate or bispecificmolecule of the invention and a pharmaceutically acceptable carrier arealso provided. In another aspect, the composition further comprises asoluble neutral-active hyaluronidase glycoprotein.

Nucleic acid molecules encoding the antibodies (e.g., cDNA), orantigen-binding portions thereof (e.g., variable regions and/or CDRs),of the invention also are provided, as well as expression vectorscomprising such nucleic acids and host cells comprising such expressionvectors. Methods for producing anti-ICOS antibodies by expressing theantibody in such host cells and isolating the antibody from the hostcell are also provided.

In one aspect, the isolated antibody has reduced antibody-dependentcell-mediated cytotoxicity (ADCC) activity compared to an IgG1 controlantibody.

In another aspect, the invention provides methods of stimulating immuneresponses using anti-ICOS antibodies, or antigen-binding portionsthereof, of the invention. In one embodiment, the method includesstimulating an antigen-specific T cell response by contacting T cellswith an antibody, or an antigen-binding portion thereof, of theinvention, such that an antigen-specific T cell response is stimulated.In another embodiment, interleukin-2 production by the antigen-specificT cell is stimulated. In yet another embodiment, the subject has atumor(s), and an immune response against the tumor is stimulated. Inanother embodiment, the subject has a virus, and an immune responseagainst the virus is stimulated.

In yet another aspect, the invention provides a method for inhibitinggrowth of tumor cells in a subject comprising administering to thesubject an antibody, or antigen-binding portion thereof, of theinvention, such that growth of the tumor is inhibited in the subject. Inanother aspect, the invention provides a method for treating viralinfection in a subject comprising administering to the subject anantibody, or antigen-binding portion thereof, of the invention such thatthe viral infection is treated in the subject. Such methods compriseadministering an antibody, or an antigen-binding portion thereof, acomposition, bispecific, or immunoconjugate of the invention.

In yet another aspect, the invention provides a method for stimulatingan immune response in a subject comprising administering to the subjectan antibody, or antigen-binding portion thereof, of the invention, e.g.,in combination with at least one additional therapeutic agent, such asan anti-PD-1 antibody, an anti-PD-L1 antibody and/or an anti-CTLA-4antibody, such that an immune response is stimulated in the subject, forexample to inhibit tumor growth or to stimulate an anti-viral response.In one embodiment, the additional immunostimulatory antibody is ananti-PD-1 antibody. In another embodiment, the additionalimmunostimulatory agent is an anti-PD-L1 antibody. In yet anotherembodiment, the additional immunostimulatory agent is an anti-CTLA-4antibody. In yet another embodiment, an antibody, or antigen-bindingportion thereof, of the invention is administered with a cytokine (e.g.,IL-2, modified IL-2, and/or IL-21), or a costimulatory antibody (e.g.,an anti-CD137 and/or anti-GITR antibody). In some embodiments, theantibodies are, for example, human, chimeric or humanized antibodies.

In one embodiment, the isolated antibody is administered with one ormore additional therapeutic agent(s) to the human subject. In anotherembodiment, the additional therapeutic agent is a chemotherapeuticagent.

Also provided herein are methods for treating cancer in a subject (e.g.,a human patient), comprising administering to the patient an anti-ICOSantibody, or a combination of an anti-ICOS antibody and at least oneadditional antibody (e.g., an anti-PD-1 antibody, an anti-PD-L1antibody, and/or an anti-CTLA-4 antibody), wherein the anti-ICOSantibody, or combination of antibodies, are administered according to aparticular dosage regimen (i.e., at a particular dose amount andaccording to a specific dosing schedule). In one aspect, the methodcomprises at least one administration cycle and, for each of the atleast one cycles, at least one dose of the antibody is administered at adose of about 375 mg. In another aspect, the antibody is administered inan amount or frequency sufficient to achieve and/or maintain a receptoroccupancy of less than about 80%. In another embodiment, the methodcomprises administration at an interval of once a week, once every twoweeks, once every three weeks, once every four weeks, once every fiveweeks, once every six weeks, once every seven weeks, once every eightweeks, once every nine weeks, once every ten weeks, once every elevenweeks, or once every twelve weeks.

The methods disclosed herein include treatment of cancers, such ascolorectal cancer (CRC), head and neck squamous cell carcinoma (HNSCC),non-small cell lung cancer (NSCLC), prostate cancer (PRC), urothelialcarcinoma (UCC), bladder cancer, breast cancer, uterine/cervical cancer,ovarian cancer, testicular cancer, esophageal cancer, gastrointestinalcancer, pancreatic cancer, colon cancer, kidney cancer, stomach cancer,germ cell cancer, bone cancer, liver cancer, thyroid cancer, skincancer, neoplasm of the central nervous system, lymphoma, leukemia,myeloma, sarcoma, or virus-related cancer.

In yet another embodiment, the antibodies are formulated for intravenousadministration. In another embodiment, the antibodies are formulated forsubcutaneous administration. In another embodiment, the antibodies areadministered simultaneously (e.g., in a single formulation orconcurrently as separate formulations). Alternatively, in anotherembodiment, the antibodies are administered sequentially (e.g., asseparate formulations).

The efficacy of the treatment methods provided herein can be assessedusing any suitable means. In some embodiments, the treatment reducestumor size, reduces the number of metastatic lesions over time, producesa complete response, produces a partial results, and/or results instable disease.

In another aspect, the invention provides anti-ICOS antibodies, orantigen-binding portions thereof, and compositions of the invention foruse in the foregoing methods, or for the manufacture of a medicament foruse in the foregoing methods (e.g., for treatment of variousconditions).

Also provided are kits that include a pharmaceutical compositioncontaining an anti-ICOS antibody in a therapeutically effective amountadapted for use in the methods described herein. In another embodiment,the kit includes an anti-ICOS antibody and another antibody (e.g., ananti-PD-1 antibody, an anti-PD-L1 antibody, and/or an anti-CTLA-4antibody) in therapeutically effective amounts adapted for use in themethods described herein. For example, the kit comprises:

(a) a dose of an anti-ICOS antibody;

(b) a dose of an anti-PD-1 antibody, an anti-PD-L1 antibody, and/or ananti-CTLA-4 antibody; and

(c) instructions for using the antibodies in a method of the invention.

In another aspect, an anti-ICOS antibody is provided for administration(or co-administration with another antibody, e.g., an anti-PD-1antibody, an anti-PD-L1 antibody, and/or an anti-CTLA-4 antibody)according to the methods described herein.

Other features and advantages of the instant disclosure will be apparentfrom the following detailed description and examples, which should notbe construed as limiting. The contents of all references, GenBankentries, patents and published patent applications cited throughout thisapplication are expressly incorporated herein by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the human ICOS sequence (SEQ ID NO: 1). The results ofepitope binding analysis for ICOS.4 using hydrogen/deuterium exchangemass spectrometry (HDX-MS) are shown with the ICOS.4 epitope in bold andunderlined.

FIG. 2 shows a portion of the sequence of human IgG1f constant domain(SEQ ID NO: 52, renumbered as residues 118-446) that can be used in theFc sequence variants disclosed herein. Residues set forth in bold areexample residues subject to variation. The altered amino acid isprovided in bold below the particular residue. The D270E substitution isunderlined. A C-terminal lysine (K) residue has been omitted from thesequence of SEQ ID NO: 52 but, in some embodiments, is present.Likewise, in some embodiments, nucleic acids encoding these embodimentsinclude nucleotides encoding the extra lysine at the 3′ end of thenucleic acid.

FIG. 3 shows the sequence alignment of the human heavy and light chaingermline sequences used for humanizing the parental hamster antibody(C398.4). VH3-15 was selected for the heavy chain, and VKI O18 wasselected for the light chain based on framework sequence homology. Humangermline FW4, JK3, was also selected for the light chain based onsequence homology. Human germline FW4, JH4, was selected for the heavychain based on sequence similarity, and it did not contain residues thatcould pose a potential liability risk. Asterisks and underliningindicate the amino acid residues that differ between the germlinesequences and the parental hamster antibody sequence (C398.4).

FIG. 4 shows the heavy and the light chain variable region sequences ofthe anti-ICOS antibody ICOS.33 IgG1f S267E. The CDR1, 2, and 3 regionsof the heavy and the light chain variable regions are in bold,underlined, and labeled.

FIGS. 5A and 5B are graphs that show interferon-gamma (IFN-γ) productionand cell proliferation induced by ICOS.33 IgG1f S267E in co-cultures ofCD25− CD4+ T cells and CHO-OKT3-CD32A cells.

FIG. 6 is a graph that illustrates IFN-γ induction by anti-ICOSantibodies in a CD25− CD4+ T cell and B cell SEB co-culture assay.

FIGS. 7A and 7B are a graphs that show IL-10 and IFN-γ induction in anSEB stimulated Tfh and naive B cell co-culture assay. Average: 4.4-foldinduction.

FIGS. 8A and 8B are graphs that show the elimination of Teff suppressionby Tregs with anti-ICOS antibody costimulation.

FIGS. 9A and 9B are graphs that compare the ability of ICOS.33 IgG1fS267E and ICOS.33 IgG1 to induce ADCC using cells from two differentdonors (Donors 9 and 12).

FIG. 10 is a graph of results from an ELISA assay comparing the abilityof ICOS.33 IgG1f S267E and ICOS.33 IgG1 to bind C1q component of humancomplement.

FIGS. 11A-C are graphs that show the anti-tumor activity of ICOS Fcvariants, ICOS IgG1 SE (“ICOS hg1 SE”) and ICOS IgG1 (“ICOS hg1”)antibodies, and an IgG1 isotype control antibody (“hIgG1”) in an MC38tumor model.

FIGS. 12A-E are graphs that show the tumor growth curves by treatmentgroup. Mice were treated with isotype control mG1, ICOS.1 mg1 D265A,ICOS.4 mg1, ICOS.4 hg1, or ICOS.4 mg2a on days 7, 10, and 14 post-Sa1Ncell implantation.

FIGS. 13A and 13B are graphs that illustrate mean and median tumorgrowth curves by treatment group. Mice were treated with isotype controlmG1, ICOS.1 mg1 D265A, ICOS.4 mg1, ICOS.4 hg1, or ICOS.4 mg2a on days 7,10, and 14 post-Sa1N cell implantation.

FIGS. 14A-D are graphs that show the percentage of Foxp3+ Treg cells,CD4+ Teff cells, and CD8+ T cells in tumors at Day 15. Mice were treatedwith isotype control mG1, ICOS.1 mg1 D265A, ICOS.4 mg1, ICOS.4 hg1, orICOS.4 mg2a on days 7, 10, and 14 post-Sa1N cell implantation.

FIGS. 15A-J are graphs that show tumor growth curves for individual miceby treatment group: isotype control mIgG1, anti-PD-1 mIgG1 D265A(“PD-1”), and/or anti-ICOS.4 mIgG1 (“ICOS.4 mg1”) antibodies.

FIGS. 16A and 16B are graphs that show the mean and median tumor growthcurves by treatment group: isotype control mIgG1, anti-PD-1 mg1, and/oranti-ICOS.4 mIgG1 (“ICOS.4 mg1”) antibodies.

FIGS. 17A-D are graphs that show the mean (SEM) percentages of Foxp3+,CD8+, Ki-67, and Granzyme B in tumors. Mice were treated with isotypecontrol mIgG1, anti-PD-1 mg1, and/or anti-ICOS.4 mIgG1 (“ICOS.4 mg1”)antibodies.

FIGS. 18A-I are graphs that show the tumor growth curves for individualmice by treatment group: isotype control mIgG1, anti-PD-1 mIgG1 D265A(“PD-1”), and/or anti-ICOS.4 mIgG1 (“ICOS”) antibodies.

FIGS. 19A and 19B are graphs that show the mean and median tumor growthcurves by treatment group: isotype control mIgG1, anti-PD-1 mIgG1 D265A(“PD-1”), and/or anti-ICOS.4 mIgG1 (“ICOS”) antibodies.

FIGS. 20A-D are graphs that show the percentage of Foxp3+ Treg cells,CD4+ Teff cells, and CD8+ T cells in tumors. Mice were treated withisotype control mIgG1, anti-PD-1 mIgG1 D265A (“PD-1”), and/oranti-ICOS.4 mIgG1 (“ICOS”) antibodies.

FIGS. 21A-C are graphs that show the mean percentages of Ki-67 intumors. Mice were treated with isotype control mIgG1, anti-PD-1 mIgG1D265A (“PD-1”), and/or anti-ICOS.4 mIgG1 (“ICOS”) antibodies.

FIGS. 22A-D are graphs that show the expression of ICOS-L on B cells inspleen and PBMC. Mice were treated with isotype control mIgG1, anti-PD-1mIgG1 D265A (“PD-1”), and/or anti-ICOS.4 mIgG1 (“ICOS”) antibodies.

FIGS. 23A-F are graphs that show the tumor growth curves for individualmice by treatment group: isotype control mIgG1, anti-CTLA-4 mIgG2b(“CTLA-4 mg2b”), anti-ICOS.4 mIgG1 (“ICOS.4 mg1”), and/or anti-ICOS.4mIgG2a (“ICOS.4 mg2a”) antibodies.

FIGS. 24A and 24B are graphs that show the mean and median tumor growthcurves by treatment group: isotype control mIgG1, anti-CTLA-4 mIgG2b(“CTLA-4 mg2b”), anti-ICOS.4 mIgG1 (“ICOS.4 mg1”), and/or anti-ICOS.4mIgG2a (“ICOS.4 mg2a”) antibodies.

FIGS. 25A and 25B are graphs that show ICOS.33 IgG1f S267E binding tohuman, cynomolgus monkey, rat and mouse T cells, as measured using FACS.

FIGS. 26A and 26B are graphs that show that the ICOS.33 IgG1f antibodyhas greater binding avidity to CD4+ T cells as calculated by EC50 valuescompared to two competitor anti-ICOS antibodies.

FIG. 27 is a schematic illustrating a dose escalation clinical trialstudy using anti-ICOS antibody in combination with anti-PD-1 antibodyand/or anti-CTLA-4 antibody.

FIG. 28 is a graph showing the effects of increasing doses of anti-ICOSantibody, ICOS.33 IgG1f S267E, in combination with an anti-PD1 antibodyand the effect on tumor growth inhibition in a mouse model.

DETAILED DESCRIPTION

The present invention provides isolated antibodies, such as monoclonalantibodies, e.g., humanized or human monoclonal antibodies, thatspecifically bind to human ICOS (“huICOS”) and have agonist activity tostimulate an immune response. In some embodiments, the antibodiesdescribed herein comprise particular structural features such as CDRregions comprising particular amino acid sequences. In otherembodiments, the antibodies compete for binding to human ICOS proteinwith, or bind to the same epitope as, the antibodies of the presentinvention.

Further provided herein are methods of making such antibodies,immunoconjugates, and bispecific molecules comprising such antibodies orantigen-binding fragments thereof, and pharmaceutical compositionsformulated to contain the antibodies or antibody fragments. Alsoprovided herein are methods of using the antibodies, either alone or incombination with other agents, e.g., other immunostimulatory agents(e.g., antibodies), to enhance the immune response to, for example treatcancer and/or infections. Accordingly, the anti-huICOS antibodiesdescribed herein may be used to treat a variety of conditions,including, for example, to inhibit tumor growth.

Definitions

In order that the present description may be more readily understood,certain terms are first defined. Additional definitions are set forththroughout the detailed description. The headings provided herein arenot limitations of the various aspects of the disclosure, which can beunderstood by reference to the specification as a whole. Accordingly,the terms defined immediately below are more fully defined by referenceto the specification in its entirety.

As used herein, ICOS refers to “inducible T-cell co-stimulator” proteinthat in humans is encoded by the ICOS gene. ICOS is also known as“inducible co-stimulator,” “activation-inducible lymphocyteimmunomediatory molecule,” AILIM, CVID1, and CD278. Human ICOS isfurther described at GENE ID NO: 29851 and MIM (Mendelian Inheritance inMan): 604558. The sequence of human ICOS (NP_036224.1), including a 20amino acid signal sequence, is provided as SEQ ID NO: 1 and shown inFIG. 1.

Below are the amino acid sequences of the two human ICOS isoforms.

Isoform 1 (Q9Y6W8) (SEQ ID NO: 1)MKSGLWYFFL FCLRIKVLTG EINGSANYEM FIFHNGGVQILCKYPDIVQQ FKMQLLKGGQ ILCDLTKTKG SGNTVSIKSLKFCHSQLSNN SVSFFLYNLD HSHANYYFCN LSIFDPPPFKVTLTGGYLHI YESQLCCQLK FWLPIGCAAF VVVCILGCILICWLTKKKYS SSVHDPNGEY MFMRAVNTAK KSRLTDVTL Isoform 2 (Q9Y6W8-2)(SEQ ID NO: 205) MKSGLWYFFLFCLRIKVLTGEINGSANYEMFIFHNGGVQILCKYPDIVQQFKMQLLKGGQILCDLTKTKGSGNTVSIKSLKFCHSQLSNNSVSFFLYNLDHSHANYYFCNLSIFDPPPFKVTLTGGYLHIYESQLCCQLKFWLPIG CAAFVVVCILGCILICWLTKKM

The signal sequence of isoforms 1 and 2 correspond to amino acids 1-20(underlined above). Thus, the mature isoforms 1 and 2 consist of aminoacids 21-199 of SEQ ID NO: 1 and amino acids 21-158 of SEQ ID NO: 205.

ICOS interacts with ICOS ligand (ICOS-L), which is also known as ICOSL,ICOS-LG, LICOS, B7H2, B7-H2, B7RP1, B7RP-1, CD275 and GL50. Human ICOS-Lis further described at GENE ID NO: 23308 and MIM: 605717. The sequenceof human ICOS-L (NP_001269979.1), including 18 amino acid signalsequence, is provided at SEQ ID NO: 2. Thus, the mature form of ICOS-Lconsists of amino acids 19-302 of SEQ ID NO: 2.

The term “antibody” or “immunoglobulin,” which is used interchangeablyherein, refers to a protein comprising at least two heavy (H) chains andtwo light (L) chains inter-connected by disulfide bonds. Each heavychain is comprised of a heavy chain variable region (abbreviated hereinas V_(H)) and a heavy chain constant region (abbreviated herein as CH).In certain antibodies, e.g., naturally occurring IgG antibodies, theheavy chain constant region is comprised of a hinge and three domains,CH1, CH2 and CH3. In certain antibodies, e.g., naturally occurring IgGantibodies, each light chain is comprised of a light chain variableregion (abbreviated herein as V_(L)) and a light chain constant region.The light chain constant region is comprised of one domain (abbreviatedherein as CL). The V_(H) and V_(L) regions can be further subdividedinto regions of hypervariability, termed complementarity determiningregions (CDR), interspersed with regions that are more conserved, termedframework regions (FR). Each V_(H) and V_(L) is composed of three CDRsand four FRs, arranged from amino-terminus to carboxy-terminus in thefollowing order: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4. The variableregions of the heavy and light chains contain a binding domain thatinteracts with an antigen. The constant regions of the antibodies canmediate the binding of the immunoglobulin to host tissues or factors,including various cells of the immune system (e.g., effector cells) andthe first component (C1q) of the classical complement system. A heavychain may have the C-terminal lysine or not. Unless specified otherwiseherein, the amino acids in the variable regions are numbered using theKabat numbering system and those in the constant regions are numberedusing the EU system. An immunoglobulin can be from any of the knownisotypes, including IgA, secretory IgA, IgD, IgE, IgG, and IgM. The IgGisotype is divided in subclasses in certain species: IgG1, IgG2, IgG3and IgG4 in humans, and IgG1, IgG2a, IgG2b and IgG3 in mice. In certainembodiments, the anti-ICOS antibodies described herein are of the IgG1subtype. Immunoglobulins, e.g., IgG1, exist in several allotypes, whichdiffer from each other in at most a few amino acids. “Antibody”includes, by way of example, both naturally occurring and non-naturallyoccurring antibodies; monoclonal and polyclonal antibodies; chimeric andhumanized antibodies; human and nonhuman antibodies and wholly syntheticantibodies.

As used herein, an “IgG antibody” has the structure of a naturallyoccurring IgG antibody, i.e., it has the same number of heavy and lightchains and disulfide bonds as a naturally occurring IgG antibody of thesame subclass. For example, an anti-ICOS IgG1, IgG2, IgG3 or IgG4antibody consists of two heavy chains (HCs) and two light chains (LCs),wherein the two heavy chains and light chains are linked by the samenumber and location of disulfide bridges that occur in naturallyoccurring IgG1, IgG2, IgG3 and IgG4 antibodies, respectively (unless theantibody has been mutated to modify the disulfide bonds).

An “antigen” is a molecule or substance that triggers an immune responseand to which an antibody binds. Antibodies typically bind specificallyto their cognate antigen with high affinity, reflected by a dissociationconstant (K_(D)) of 10⁻⁷ to 10⁻¹¹ M or less. Any K_(D) greater thanabout 10⁻⁶ M is generally considered to indicate nonspecific binding. Asused herein, an antibody that “binds specifically” to an antigen refersto an antibody that binds to the antigen and, in some cases,substantially identical antigens, with high affinity, which means havinga K_(D) of 10⁻⁷ M or less, 10⁻⁸ M or less, 5×10⁻⁹ M or less, or between10⁻⁸ M and 10⁻¹⁰ M or less, but does not bind with high affinity tounrelated antigens. An antigen is “substantially identical” to a givenantigen if it exhibits a high degree of sequence identity to the givenantigen, for example, if it exhibits at least 80%, at least 90%, atleast 95%, at least 97%, or at least 99% sequence identity to thesequence of the given antigen. By way of example, an antibody that bindsspecifically to human ICOS, in some embodiments, also cross-reacts withICOS antigens from certain non-human primate species (e.g., cynomolgusmonkey), but does not cross-react with ICOS from other species or withan antigen other than ICOS.

As used herein, the term “antigen-binding portion” or “antigen-bindingfragment” of an antibody refers to one or more parts of an antibody thatretain the ability to specifically bind to an antigen (e.g., humanICOS). It has been shown that the antigen-binding function of anantibody can be performed by fragments or portions of a full-lengthantibody. Examples of binding fragments encompassed within the term“antigen-binding portion” or “antigen-binding fragment” of an antibody,e.g., an anti-ICOS antibody described herein, include:

(1) a Fab fragment (fragment from papain cleavage) or a similarmonovalent fragment consisting of the V_(L), V_(H), LC and CH1 domains;

(2) a F(ab′)2 fragment (fragment from pepsin cleavage) or a similarbivalent fragment comprising two Fab fragments linked by a disulfidebridge at the hinge region;

(3) a Fd fragment consisting of the V_(H) and CH1 domains;

(4) a Fv fragment consisting of the V_(L) and V_(H) domains of a singlearm of an antibody,

(5) a single domain antibody (dAb) fragment (Ward et al., (1989) Nature341:544-46), which consists of a V_(H) domain;

(6) an isolated complementarity determining region (CDR); and

(7) a combination of two or more isolated CDRs, which can optionally bejoined by a synthetic linker. Furthermore, although the two domains ofthe Fv fragment, V_(L) and V_(H), are coded for by separate genes, theycan be joined, using recombinant methods, by a synthetic linker thatenables them to be made as a single protein chain in which the V_(L) andV_(H) regions pair to form monovalent molecules (known as single chainFv (scFv); see e.g., Bird et al. (1988) Science 242:423-426; and Hustonet al. (1988) Proc. Natl. Acad. Sci. USA 85:5879-5883). Such singlechain antibodies are also intended to be encompassed within the term“antigen-binding portion” or “antigen-binding fragment” of an antibody.These antibody fragments are obtained using conventional techniquesknown to those with skill in the art, and the fragments are screened forutility in the same manner as are intact antibodies. Antigen-bindingportions can be produced by recombinant DNA techniques, or by enzymaticor chemical cleavage of intact immunoglobulins.

The term “acceptor human framework” refers to a framework comprising theamino acid sequence of a light chain variable domain (V_(L)) frameworkor a heavy chain variable domain (V_(H)) framework derived from a humanimmunoglobulin framework or a human consensus framework. An acceptorhuman framework “derived from” a human immunoglobulin framework or ahuman consensus framework may have the same amino acid sequence as thenaturally-occurring human immunoglobulin framework or human consensusframework, or it may have amino acid sequence changes compared towild-type naturally-occurring human immunoglobulin framework or humanconsensus framework. In some embodiments, the number of amino acidchanges are 10, 9, 8, 7, 6, 5, 4, 3, or 2, or 1. In some embodiments,the V_(L) acceptor human framework is identical in sequence to the V_(L)human immunoglobulin framework sequence or human consensus frameworksequence.

“Hinge,” “hinge domain,” or “hinge region,” or “antibody hinge region”refers to the domain of a heavy chain constant region that joins the CH1domain to the CH2 domain and comprises upper, middle, and lowerportions. (Roux et al. (1998) J. Immunol. 161:4083). Depending on itsamino acid sequence, the hinge provides varying levels of flexibilitybetween the antigen binding domain and effector region of an antibodyand also provides sites for intermolecular disulfide bonding between thetwo heavy chain constant regions. As used herein, a hinge starts at E216and ends at G237 for all IgG isotypes (by EU numbering). Id. Thesequences of wildtype IgG1, IgG2, IgG3 and IgG4 hinges are show in Table1.

TABLE 1 Hinge Region Sequences C-terminal Ig Type C_(H)1* Upper HingeMiddle Hinge Lower Hinge IgG1 VDKRV EPKSCDKTHT CPPCP APELLGG(SEQ ID NO: 66) (SEQ ID NO: 67) (SEQ ID NO: 68) (SEQ ID NO: 69) IgG2VDKTV ERK CCVECPPCP APPVAG (SEQ ID NO: 70) (SEQ ID NO: 71)(SEQ ID NO: 72) IgG3 (17-15-15- VDKRV ELKTPLGDTTHT CPRCP APELLGG 15)(SEQ ID NO: 66) (SEQ ID NO: 73) (EPKSCDTPPPCPRCP)₃ (SEQ ID NO: 69)(SEQ ID NO: 74) IgG3 (17-15-15) VDKRV ELKTPLGDTTHT CPRCP APELLGG(SEQ ID NO: 66) (SEQ ID NO: 73) (EPKSCDTPPPCPRCP)₂ (SEQ ID NO: 69)(SEQ ID NO: 75) IgG3 (17-15) VDKRV ELKTPLGDTTHT CPRCP APELLGG(SEQ ID NO: 66) (SEQ ID NO: 73) (EPKSCDTPPPCPRCP)₁ (SEQ ID NO: 69)(SEQ ID NO: 76) IgG3 (15-15-15) VDKRV EPKS CDTPPPCPRCP APELLGG(SEQ ID NO: 66) (SEQ ID NO: 77) (EPKSCDTPPPCPRCP)₂ (SEQ ID NO: 69)(SEQ ID NO: 78) IgG3 (15) VDKRV EPKS CDTPPPCPRCP APELLGG (SEQ ID NO: 66)(SEQ ID NO: 77) (SEQ ID NO: 79) (SEQ ID NO: 69) IgG4 VDKRV ESKYGPP CPSCPAPEFLGG (SEQ ID NO: 66) (SEQ ID NO: 80) (SEQ ID NO: 81) (SEQ ID NO: 82)  *C-terminal amino acid sequences of the CH1 domains.

The term “hinge” includes wild-type hinges (such as those set forth inTable 1), as well as variants thereof (e.g., non-naturally-occurringhinges or modified hinges). For example, the term “IgG2 hinge” includeswildtype IgG2 hinge, as shown in Table 1, and variants having 1 or moremutations (e.g., substitutions, deletions, and/or additions), forexample, 1, 2, 3, 4, 5, 1 to 3, 1 to 5, 3 to 5 and/or at most 5, 4, 3,2, or 1 mutations. Exemplary IgG2 hinge variants include IgG2 hinges inwhich 1, 2, 3 or all 4 cysteines (C219, C220, C226 and C229) are changedto another amino acid, e.g. serine. In a specific embodiment, the IgG2hinge region has a C219S substitution. In certain embodiments, the hingecomprises sequences from at least two isotypes. For example, the hingemay comprise the upper, middle, or lower hinge from one isotype, and theremainder of the hinge from one or more other isotypes. For example, thehinge can be an IgG2/IgG1 hinge, and may comprise, e.g., the upper andmiddle hinges of IgG2 and the lower hinge of IgG1. A hinge may haveeffector function or be deprived of effector function. For example, thelower hinge of wildtype IgG1 provides effector function. The term “CH1domain” refers to the heavy chain constant region linking the variabledomain to the hinge in a heavy chain constant domain. As used herein, aCH1 domain starts at A118 and ends at V215. The term “CH2 domain” refersto the heavy chain constant region linking the hinge to the CH3 domainin a heavy chain constant domain. As used herein, a CH2 domain starts atP238 and ends at K340. The term “CH3 domain” refers to the heavy chainconstant region that is C-terminal to the CH2 domain in a heavy chainconstant domain. As used herein, a CH3 domain starts at G341 and ends atK447.

A “bispecific” or “bifunctional antibody” is an artificial hybridantibody having two different binding specificities, e.g., two differentheavy/light chain pairs, giving rise to two antigen binding sites withspecificity for different antigens. Bispecific antibodies can beproduced by a variety of methods including fusion of hybridomas orlinking of Fab′ fragments. See, e.g., Songsivilai & Lachmann, Clin. Exp.Immunol. 79:315-321 (1990); Kostelny et al., J. Immunol. 148, 1547-1553(1992).

As used herein, the term “monoclonal antibody” refers to an antibodyobtained from a population of substantially homogeneous antibodies,i.e., the individual antibodies in the population are substantiallysimilar and bind the same epitope(s) (e.g., the antibodies display asingle binding specificity and affinity), except for possible variantsthat may arise during production of the monoclonal antibody, suchvariants generally being present in minor amounts. “Monoclonal”indicates the character of the antibody as having been obtained from asubstantially homogenous population of antibodies, and does not requireproduction of the antibody by any particular method. The term “humanmonoclonal antibody” refers to an antibody from a population ofsubstantially homogeneous antibodies that displays a single bindingspecificity and that has variable and optional constant regions derivedfrom human germline immunoglobulin sequences. In one embodiment, humanmonoclonal antibodies are produced by using hybridoma method. Using thehybridoma method, a transgenic non-human animal, e.g., a transgenicmouse, is exposed to an antigen, and a white blood cell known as a Bcell produces antibodies that bind to the antigen, which is harvestedfrom the transgenic non-human animal. The isolated B cells are fusedwith an immortalized cell to produce a hybrid cell line called ahybridoma. In one embodiment, the hybridoma has a genome comprising ahuman heavy chain transgene and a light chain transgene fused to animmortalized cell.

Antigen binding fragments (including scFvs) of such immunoglobulins arealso encompassed by the term “monoclonal antibody” as used herein.Monoclonal antibodies are highly specific, being directed against asingle antigenic site. Furthermore, in contrast to conventional(polyclonal) antibody preparations, which typically include differentantibodies directed against different epitopes on the antigen, eachmonoclonal antibody is directed against a single epitope. Monoclonalantibodies can be prepared using any art recognized technique and thosedescribed herein such as, for example, a hybridoma method, a transgenicanimal, recombinant DNA methods (see, e.g., U.S. Pat. No. 4,816,567), orusing phage antibody libraries using the techniques described in, forexample, U.S. Pat. No. 7,388,088 and PCT Pub. No. WO 00/31246).Monoclonal antibodies include chimeric antibodies, human antibodies, andhumanized antibodies and may occur naturally or be producedrecombinantly.

As used herein, the term “recombinant human antibody” includes all humanantibodies that are prepared, expressed, created or isolated byrecombinant means, such as (1) antibodies isolated from an animal (e.g.,a mouse) that is transgenic or transchromosomal for human immunoglobulingenes or a hybridoma prepared therefrom, (2) antibodies isolated from ahost cell transformed to express the antibody, e.g., from atransfectoma, (3) antibodies isolated from a recombinant, combinatorialhuman antibody library, and (4) antibodies prepared, expressed, created,or isolated by any other means that involve splicing of humanimmunoglobulin gene sequences to other DNA sequences. Such recombinanthuman antibodies comprise variable and constant regions that useparticular human germline immunoglobulin sequences are encoded by thegermline genes, but include subsequent rearrangements and mutations thatoccur, for example, during antibody maturation. As known in the art(see, e.g., Lonberg (2005) Nature Biotech. 23(9): 1117-1125), thevariable region contains the antigen binding domain, which is encoded byvarious genes that rearrange to form an antibody specific for a foreignantigen. In addition to rearrangement, the variable region can befurther modified by multiple single amino acid changes (referred to assomatic mutation or hypermutation) to increase antibody affinity to theforeign antigen. The constant region will change in further response toan antigen (i.e., isotype switch). Thus, the rearranged and somaticallymutated nucleic acid molecules that encode the light chain and heavychain immunoglobulin polypeptides in response to an antigen cannot havesequence identity with the original nucleic acid molecules, but insteadwill be substantially identical or similar (e.g., have at least 80%identity).

As used herein, a “human antibody” refers to an antibody having variableregions in which both the framework and CDR regions are derived fromhuman germline immunoglobulin sequences. Furthermore, if the antibodycontains a constant region, the constant region also is derived fromhuman germline immunoglobulin sequences. The anti-huICOS antibodiesdescribed herein may include amino acid residues not encoded by humangermline immunoglobulin sequences (e.g., because of mutations introducedby random or site-specific mutagenesis in vitro or by somatic mutationin vivo). However, the term “human antibody” is not intended to includeantibodies in which CDR sequences derived from the germline of anothernon-human mammalian species, such as a mouse, have been grafted ontohuman framework sequences. As used herein, the terms “human” and “fullyhuman” antibodies are used interchangeably.

A “humanized” antibody refers to an antibody in which some, most, or allof the amino acids outside the CDR domains of a non-human antibody arereplaced with corresponding amino acids derived from human antibodies.In one embodiment of a humanized form of an antibody, some, most, or allof the amino acids outside the CDR domains have been replaced with aminoacids from human antibodies, whereas some, most, or all amino acidswithin one or more CDR regions are unchanged. Small additions,deletions, insertions, substitutions, or modifications of amino acidsare permissible as long as they do not prevent the antibody from bindingto a particular antigen. A “humanized” antibody retains an antigenicspecificity similar to that of the original antibody.

A “chimeric antibody” refers to an antibody in which the variableregions are derived from one species and the constant regions arederived from another species, such as an antibody in which the variableregions are derived from a mouse antibody and the constant regions arederived from a human antibody. A “hybrid” antibody refers to an antibodyhaving heavy and light chains of different type, such as a mouse orhamster (parental) heavy chain and a humanized light chain, or viceversa. Chimeric or hybrid antibodies can be constructed, for example bygenetic engineering, from immunoglobulin gene segments belonging todifferent species.

As used herein, “isotype” refers to the antibody class (e.g., IgG(including IgG1, IgG2, IgG3, and IgG4), IgM, IgA (including IgA1 andIgA2), IgD, and IgE antibody) that is encoded by the heavy chainconstant region genes of the antibody.

“Allotype” refers to naturally occurring variants within a specificisotype group. (See, e.g., Jefferis et al. (2009) mAbs 1:1).

The terms “an antibody recognizing an antigen” and “an antibody specificfor an antigen” are used interchangeably herein with the term “anantibody that binds specifically to an antigen.”

As used herein, an “isolated antibody” refers to an antibody that issubstantially free of other proteins and cellular materials. As usedherein, an “effector function” refers to the interaction of an antibodyFc region with an Fc receptor or ligand, or a biochemical event thatresults therefrom. Exemplary “effector functions” include C1q binding,complement dependent cytotoxicity (CDC), Fc receptor binding,FcγR-mediated effector functions such as ADCC and antibody dependentcell-mediated phagocytosis (ADCP), and downregulation of a cell surfacereceptor (e.g., the B cell receptor; BCR). Such effector functionsgenerally require the Fc region to be combined with a binding domain(e.g., an antibody variable domain).

An “Fc receptor” or “FcR” is a receptor that binds to the Fc region ofan immunoglobulin. FcRs that bind to an IgG antibody comprise receptorsof the FcγR family, including allelic variants and alternatively splicedforms of these receptors. The FcγR family consists of three activating(FcγRI, FcγRIII, and FcγRIV in mice; FcγRIA, FcγRIIA, and FcγRIIIA inhumans) and one inhibitory (FcγRIIb, or equivalently FcγRIIB) receptor.Various exemplary properties of human FcγRs are summarized in Table 2.The majority of innate effector cell types co-express one or moreactivating FcγR and the inhibitory FcγRIIb, whereas natural killer (NK)cells selectively express one activating Fc receptor (FcγRIII in miceand FcγRIIIA in humans) but not the inhibitory FcγRIIb in mice andhumans. Human IgG1 binds to most human Fc receptors and is consideredequivalent to murine IgG2a with respect to the types of activating Fcreceptors that it binds to.

TABLE 2 Exemplary Properties of Human FcγRs Allelic Affinity for Fcγvariants human IgG Isotype preference Cellular distribution FcγRI NoneHigh (K_(D =) IgG1 = 3 > 4 >> 2 Monocytes, macrophages, described about10 nM) activated neutrophils, dendritic cells FcγRIIA H131 Low to mediumIgG1 > 3 > 2 > 4 Neutrophils, monocytes, R131 Low IgG1 > 3 > 4 > 2macrophages, eosinophils, dendritic cells, platelets FcγRIIIA V158Medium IgG1 = 3 >> 4 > 2 Natural killer (NK) cells, F158 Low IgG1 = 3 >>4 > 2 monocytes, macrophages, mast cells, eosinophils, dendritic cellsFcγRIIb I232 Low IgG1 = 3 = 4 > 2 B cells, monocytes, T232 Low IgG1 = 3= 4 > 2 macrophages, dendritic cells, mast cells

As used herein, an “Fc region” (fragment crystallizable region) or “Fcdomain” or “Fc” refers to the C-terminal region of the heavy chain of anantibody that mediates the binding of the immunoglobulin to host tissuesor factors, including binding to Fc receptors located on various cellsof the immune system (e.g., effector cells) or to the first component(C1q) of the classical complement system. Thus, an Fc region comprisesthe constant region of an antibody excluding the first constant regionimmunoglobulin domain (e.g., CH1 or CL). In IgG, IgA, and IgD antibodyisotypes, the Fc region comprises CH2 and CH3 constant domains in eachof the antibody's two heavy chains; IgM and IgE Fc regions comprisethree heavy chain constant domains (CH domains 2-4) in each polypeptidechain. For IgG, the Fc region comprises immunoglobulin domains Cγ2 andCγ3 and the hinge between Cγ1 and Cγ2. Although the boundaries of the Fcregion of an immunoglobulin heavy chain might vary, the human IgG heavychain Fc region is usually defined to stretch from an amino acid residueat position C226 or P230 (or an amino acid between these two aminoacids) to the carboxy-terminus of the heavy chain, wherein the numberingis according to the EU index as in Kabat. (Kabat et al. (1991) Sequencesof Proteins of Immunological Interest, National Institutes of Health,Bethesda, Md.). The CH2 domain of a human IgG Fc region extends fromabout amino acid 231 to about amino acid 340, whereas the CH3 domain ispositioned on C-terminal side of a C_(H2) domain in an Fc region, i.e.,it extends from about amino acid 341 to about amino acid 447 of an IgG(including a C-terminal lysine). As used herein, the Fc region may be anative sequence Fc, including any allotypic variant, or a variant Fc(e.g., a non-naturally occurring Fc). Fc region refers to this region inisolation or in the context of an Fc-comprising protein polypeptide suchas a “binding protein comprising an Fc region,” also referred to as an“Fc fusion protein” (e.g., an antibody or immunoadhesin).

An “Fc region” (fragment crystallizable region) or “Fc domain” or “Fc”refers to the C-terminal region of the heavy chain of an antibody thatmediates the binding of the immunoglobulin to host tissues or factors,including binding to Fc receptors located on various cells of the immunesystem (e.g., effector cells) or to the first component (C1q) of theclassical complement system. Thus, an Fc region comprises the constantregion of an antibody excluding the first constant region immunoglobulindomain (e.g., CH1 or CL). In IgG, IgA and IgD antibody isotypes, the Fcregion comprises two identical protein fragments, derived from thesecond (CH2) and third (CH3) constant domains of the antibody's twoheavy chains. In IgM and IgE antibody isotopes, the Fc regions comprisethree heavy chain constant domains (CH domains 2-4) in each polypeptidechain. For IgG, the Fc region comprises immunoglobulin domains CH2 andCH3 and the hinge between CH1 and CH2 domains. Although the definitionof the boundaries of the Fc region of an immunoglobulin heavy chainmight vary, as defined herein, the human IgG heavy chain Fc region isdefined to stretch from an amino acid residue D221 for IgG1, V222 forIgG2, L221 for IgG3 and P224 for IgG4 to the carboxy-terminus of theheavy chain, wherein the numbering is according to the EU index as inKabat (Kabat, et al., 1991). The CH2 domain of a human IgG Fc regionextends from amino acid 237 to amino acid 340, and the CH3 domain ispositioned on C-terminal side of a CH2 domain in an Fc region, i.e., itextends from amino acid 341 to amino acid 447 or 446 (if the C-terminallysine residue is absent) or 445 (if the C-terminal glycine and lysineresidues are absent) of an IgG. As used herein, the Fc region can be anative sequence Fc, including any allotypic variant, or a variant Fc(e.g., a non-naturally occurring Fc). Fc can also refer to this regionin isolation or in the context of an Fc-comprising protein polypeptidesuch as a “binding protein comprising an Fc region,” also referred to asan “Fc fusion protein” (e.g., an antibody or immunoadhesin).

A “native sequence Fc region” or “native sequence Fc” has an amino acidsequence that is identical to the amino acid sequence of an Fc regionfound in nature. Native sequence human Fc regions include a nativesequence human IgG1 Fc region (e.g., SEQ ID NO: 206); native sequencehuman IgG2 Fc region; native sequence human IgG3 Fc region; and nativesequence human IgG4 Fc region as well as naturally occurring variantsthereof. Native sequence Fc include the various allotypes of Fcs. (See,e.g., Jefferis et al. (2009) mAbs 1:1).

The term “epitope” or “antigenic determinant” refers to a site on anantigen (e.g., huICOS) to which an immunoglobulin or antibodyspecifically binds. Epitopes can be formed both from contiguous aminoacids (usually a linear epitope) or noncontiguous amino acids juxtaposedby tertiary folding of the protein (usually a conformational epitope).Epitopes formed from contiguous amino acids are typically, but notalways, retained on exposure to denaturing solvents, whereas epitopesformed by tertiary folding are typically lost on treatment withdenaturing solvents. An epitope typically includes at least 3, 4, 5, 6,7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, or 22 aminoacids in a unique spatial conformation.

The term “epitope mapping” refers to the process of identifying themolecular determinants on the antigen involved in antibody-antigenrecognition. Methods for determining what epitopes are bound by a givenantibody are well known in the art and include, for example,immunoblotting and immunoprecipitation assays, wherein overlapping orcontiguous peptides from (e.g., from ICOS) are tested for reactivitywith a given antibody (e.g., anti-ICOS antibody); x-ray crystallography;antigen mutational analysis, two-dimensional nuclear magnetic resonance;yeast display; and hydrogen/deuterium exchange-mass spectrometry(HDX-MS) (see, e.g., Epitope Mapping Protocols in Methods in MolecularBiology, Vol. 66, G. E. Morris, Ed. (1996)).

The term “binds to the same epitope” with reference to two or moreantibodies means that the antibodies bind to the same segment of aminoacid residues, as determined by a given method. Techniques fordetermining whether antibodies bind to the “same epitope on ICOS” withthe antibodies described herein include, for example, epitope mappingmethods, such as x-ray analyses of crystals of antigen:antibodycomplexes, which provides atomic resolution of the epitope, and HDX-MS.Other methods monitor the binding of the antibody to antigen fragments(e.g. proteolytic fragments) or to mutated variations of the antigenwhere loss of binding due to a modification of an amino acid residuewithin the antigen sequence is often considered an indication of anepitope component, such as alanine scanning mutagenesis (Cunningham &Wells (1985) Science 244:1081) or yeast display of mutant targetsequence variants (see Example 16). In addition, computationalcombinatorial methods for epitope mapping can also be used. Thesemethods rely on the ability of the antibody of interest to affinityisolate specific short peptides from combinatorial phage display peptidelibraries. Antibodies having the same V_(H) and V_(L) or the same CDR1,2 and 3 sequences are expected to bind to the same epitope.

Antibodies that “compete with another antibody for binding to a target”refer to antibodies that inhibit (partially or completely) the bindingof the other antibody to the target. Whether two antibodies compete witheach other for binding to a target, i.e., whether and to what extent oneantibody inhibits the binding of the other antibody to a target, may bedetermined using known binding competition experiments, e.g., BIACORE®surface plasmon resonance (SPR) analysis. In certain embodiments, anantibody competes with, and inhibits binding of another antibody to atarget by at least 50%, 60%, 70%, 80%, 90% or 100%. The level ofinhibition or competition may be different depending on which antibodyis the “blocking antibody” (i.e., the antibody that when combined withan antigen blocks another immunologic reaction with the antigen).Competition assays can be conducted as described, for example, in EdHarlow and David Lane, Cold Spring Harb. Protoc. 2006;doi:10.1101/pdb.prot4277 or in Chapter 11 of “Using Antibodies” by EdHarlow and David Lane, Cold Spring Harbor Laboratory Press, Cold SpringHarbor, N.Y., USA 1999. Competing antibodies bind to the same epitope,an overlapping epitope, or to adjacent epitopes (e.g., as evidenced bysteric hindrance). Two antibodies “cross-compete” if antibodies blockeach other both ways by at least 50%, i.e., regardless of whether one orthe other antibody is contacted first with the antigen in thecompetition experiment.

Competitive binding assays for determining whether two antibodiescompete or cross-compete for binding include competition for binding toT cells expressing ICOS, e.g., by flow cytometry. Other methods include:surface plasmon resonance (SPR) (e.g., BIACORE®), solid phase direct orindirect radioimmunoassay (RIA), solid phase direct or indirect enzymeimmunoassay (EIA), sandwich competition assay (see Stahli et al.,Methods in Enzymology 9:242 (1983)); solid phase direct biotin-avidinEIA (see Kirkland et al., J. Immunol. 137:3614 (1986)); solid phasedirect labeled assay, solid phase direct labeled sandwich assay (seeHarlow and Lane, Antibodies: A Laboratory Manual, Cold Spring HarborPress (1988)); solid phase direct label RIA using 1-125 label (see Morelet al., Mol. Immunol. 25(1):7 (1988)); solid phase direct biotin-avidinEIA (Cheung et al., Virology 176:546 (1990)); and direct labeled RIA.(Moldenhauer et al., Scand. J. Immunol. 32:77 (1990)).

As used herein, the terms “specific binding,” “selective binding,”“selectively binds,” and “specifically binds,” refer to antibody bindingto an epitope on a predetermined antigen. Typically, the antibody: (1)binds with an equilibrium dissociation constant (K_(D)) of approximatelyless than 10⁻⁷ M, such as approximately less than 10⁻⁸ M, 10⁻⁹ M or10⁻¹⁰ M or even lower when determined by, e.g., SPR technology in aBIACORE® 2000 SPR instrument using the predetermined antigen, e.g.,recombinant human ICOS as the analyte and the antibody as the ligand, orScatchard analysis of binding of the antibody to antigen positive cells,and (2) binds to the predetermined antigen with an affinity that is atleast two-fold greater than its affinity for binding to a non-specificantigen (e.g., BSA, casein) other than the predetermined antigen or aclosely-related antigen. Accordingly, an antibody that “specificallybinds to human ICOS” refers to an antibody that binds to soluble or cellbound human ICOS with a K_(D) of 10⁻⁷ M or less, such as approximatelyless than 10⁻⁸ M, 10⁻⁹ M or 10⁻¹⁰ M or even lower. An antibody that“cross-reacts with cynomolgus ICOS” refers to an antibody that binds tocynomolgus ICOS with a K_(D) of 10⁻⁷ M or less, such as approximatelyless than 10⁻⁸ M, 10⁻⁹ M or 10⁻¹⁰ M or even lower.

The term “k_(assoc)” or “k_(a)”, as used herein, refers to theassociation rate constant of a particular antibody-antigen interaction,whereas the term “k_(dis)” or “k_(d),” as used herein, refers to thedissociation rate constant of a particular antibody-antigen interaction.The term “K_(D)”, as used herein, refers to the equilibrium dissociationconstant, which is obtained from the ratio of k_(d) to k_(a) (i.e.,k_(d)/k_(a)) and is expressed as a molar concentration (M). K_(D) valuesfor antibodies can be determined using methods well established in theart. Available methods for determining the K_(D) of an antibody isbiolayer interferometry (BLI) analysis, such as using a ForteBio OctetRED device, SPR, preferably using a biosensor system such as a BIACORE®SPR system, or flow cytometry and Scatchard analysis.

The term “EC50”, in the context of an in vitro or in vivo assay using anantibody or antigen binding fragment thereof, refers to theconcentration of an antibody or an antigen-binding fragment thereof thatinduces a response that is 50% of the maximal response, i.e., halfwaybetween the maximal response and the baseline.

The term “binds to immobilized ICOS” refers to the ability of anantibody described herein to bind to ICOS, for example, expressed on thesurface of a cell or attached to a solid support.

The term “cross-reacts,” as used herein, refers to the ability of anantibody described herein to bind to ICOS from a different species. Forexample, an antibody described herein that binds human ICOS may alsobind ICOS from another species (e.g., cynomolgus ICOS). As used herein,cross-reactivity may be measured by detecting a specific reactivity withpurified antigen in binding assays (e.g., SPR, ELISA) or binding to, orotherwise functionally interacting with, cells physiologicallyexpressing ICOS. Methods for determining cross-reactivity includestandard binding assays as described herein, for example, by SPRanalysis using a BIACORE® 2000 SPR instrument (Biacore AB, Uppsala,Sweden), or flow cytometric techniques.

“Receptor occupancy” or “occupancy of the receptor,” as used herein,refers to the amount of agonistic antibody (e.g., the anti-ICOSantibodies described herein) that is bound to the immunostimulatoryreceptor (e.g., human ICOS). “% receptor occupancy” or “% occupancy ofthe receptor” can be calculated using the following formula: ([ΔMFI ofTest]/[ΔMFI of Total])×100. ΔMFI (change in mean fluorescence unit) iscalculated by subtracting the MFI of background staining with an isotypecontrol antibody from the MFI from the bound agonistic antibody. Thetotal receptor level is determined by adding a saturating amount ofagonistic antibody to determine the maximum expression and, therefore,MFI of the particular immunostimulatory receptor. An alternative meansto calculate total receptor expression is to use an antibody against thesame immunostimulatory receptor that does not compete with the agonisticantibody for which receptor occupancy is being calculated.

As used herein, the term “naturally-occurring” as applied to a substanceis a substance that is present in nature that has not been intentionallymodified by people. For example, a polypeptide or polynucleotidesequence that is present in an organism (including viruses) that can beisolated from a source in nature and which has not been intentionallymodified by people in the laboratory is naturally-occurring.

A “polypeptide” refers to a chain comprising at least two consecutivelylinked amino acid residues, with no upper limit on the length of thechain. One or more amino acid residues in the protein may contain amodification such as, but not limited to, glycosylation, phosphorylationor a disulfide bond. A “protein” may comprise one or more polypeptides.

The term “nucleic acid molecule,” as used herein, is intended to includeDNA molecules and RNA molecules. A nucleic acid molecule may besingle-stranded or double-stranded, and may be cDNA.

The term “cDNA” refers to a non-naturally occurring nucleic acidmolecule that has been created or derived from mRNA, i.e., thenon-coding regions have been removed.

The term “mRNA” or “messenger RNA” is a nucleic acid intermediate thatspecifies the amino acid sequence of a polypeptide during translation.

As used herein, the term “conservative sequence modifications” refers toamino acid modifications that do not significantly affect or alter thebinding characteristics of the antibody containing the amino acidsequence. Such conservative modifications include amino acidsubstitutions, additions and deletions. Modifications can be introducedinto an antibody of the invention by standard techniques known in theart, such as site-directed mutagenesis and polymerase chain reaction(PCR)-mediated mutagenesis. Conservative amino acid substitutions areones in which the amino acid residue is replaced with an amino acidresidue having a similar side chain. Families of amino acid residueshaving similar side chains have been defined in the art. These familiesinclude amino acids with basic side chains (e.g., lysine, arginine,histidine), acidic side chains (e.g., aspartic acid, glutamic acid),uncharged polar side chains (e.g., glycine, asparagine, glutamine,serine, threonine, tyrosine, cysteine, tryptophan), nonpolar side chains(e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine,methionine), beta-branched side chains (e.g., threonine, valine,isoleucine), and aromatic side chains (e.g., tyrosine, phenylalanine,tryptophan, histidine). Thus, one or more amino acid residues within theCDR regions of an antibody of the invention can be replaced with otheramino acid residues from the same side chain family and the alteredantibody can be tested for retained function (i.e., the functions setforth herein) using the functional assays described herein. In certainembodiments, a predicted nonessential amino acid residue in an anti-ICOSantibody is replaced with another amino acid residue from the same sidechain family. Methods of identifying nucleotide and amino acidconservative substitutions that do not eliminate antigen binding arewell-known in the art (see, e.g., Brummell et al., Biochem. 32:1180-1187 (1993); Kobayashi et al. Protein Eng. 12(10):879-884 (1999);and Burks et al. Proc. Natl. Acad. Sci. USA 94:412-417 (1997)).

For nucleic acids, the term “substantial homology” indicates that twonucleic acids, or designated sequences thereof, when optimally alignedand compared, are identical, with appropriate nucleotide insertions ordeletions, in at least about 80% of the nucleotides, at least about 90%to 95%, or at least about 98% to 99.5% of the nucleotides.Alternatively, substantial homology exists when the segments willhybridize under selective hybridization conditions to the complement ofthe nucleic acid strand.

For polypeptides, the term “substantial homology” indicates that twopolypeptides, or designated sequences thereof, when optimally alignedand compared, are identical, with appropriate amino acid insertions ordeletions, in at least about 80% of the amino acids, at least about 90%to 95%, or at least about 98% to 99.5% of the amino acids.

The percent identity between two sequences is a function of the numberof identical positions shared by the sequences when the sequences areoptimally aligned (i.e., % homology=(number of identicalpositions)/(total number of positions)×100), taking into account thenumber of gaps and the length of each gap, which need to be introducedfor optimal alignment of the two sequences. The comparison of sequencesand determination of percent identity between two sequences can beaccomplished using a mathematical algorithm, as described below.

The percent identity between two nucleotide sequences can be determined,e.g., using the GAP program in the GCG software package, using anwsgapdna.cmp matrix and a gap weight of 40, 50, 60, 70, or 80 and alength weight of 1, 2, 3, 4, 5, or 6. The percent identity between twonucleotide or amino acid sequences can also be determined using thealgorithm of E. Meyers and W. Miller (CABIOS, 4:11-17 (1989)), which hasbeen incorporated into the ALIGN program (version 2.0), using a PAM120weight residue table, a gap length penalty of 12 and a gap penalty of 4.In addition, the percent identity between two amino acid sequences canbe determined using the Needleman and Wunsch (J. Mol. Biol. (48):444-453(1970)) algorithm, which has been incorporated into the GAP program inthe GCG software package, using either a Blossum 62 matrix or a PAM250matrix, and a gap weight of 16, 14, 12, 10, 8, 6, or 4 and a lengthweight of 1, 2, 3, 4, 5, or 6.

The nucleic acid and protein sequences described herein can further beused as a “query sequence” to perform a search against public databases,for example, to identify related sequences. Such searches can beperformed using the NBLAST and XBLAST programs (version 2.0) ofAltschul, et al. (1990) J. Mol. Biol. 215:403-10. BLAST nucleotidesearches can be performed with the NBLAST program, score=100,wordlength=12 to obtain nucleotide sequences homologous to the nucleicacid molecules described herein. BLAST protein searches can be performedwith the XBLAST program, score=50, wordlength=3 to obtain amino acidsequences homologous to the protein molecules described herein. Toobtain gapped alignments for comparison purposes, Gapped BLAST can beused as described in Altschul et al., (1997) Nucleic Acids Res.25(17):3389-3402. When utilizing BLAST and Gapped BLAST programs, thedefault parameters of the respective programs (e.g., XBLAST and NBLAST)can be used. (See, e.g., National Center for Biotechnology Information(NCBI), available at https://www.ncbi.nlm.nih.gov/).

The nucleic acids may be present in whole cells, e.g., a host cell, in acell lysate, or in a partially purified or substantially pure form. Anucleic acid is “isolated” or “rendered substantially pure” whenpurified away from other cellular components or other contaminants,e.g., other cellular nucleic acids (e.g., the other parts of thechromosome) or proteins, by standard techniques, including alkaline/SDStreatment, CsCl banding, column chromatography, agarose gelelectrophoresis and others well known in the art. (See, F. Ausubel, etal., ed. Current Protocols in Molecular Biology, Greene Publishing andWiley Interscience, New York (1987)).

The term “vector,” as used herein, is intended to refer to a nucleicacid molecule capable of transporting another nucleic acid to which ithas been linked. One type of vector is a “plasmid,” which refers to acircular double stranded DNA loop into which additional DNA segments maybe ligated. Another type of vector is a viral vector, wherein additionalDNA segments may be ligated into the viral genome. Certain vectors arecapable of autonomous replication in a host cell into which they areintroduced (e.g., bacterial vectors having a bacterial origin ofreplication and episomal mammalian vectors). Other vectors (e.g.,non-episomal mammalian vectors) can be integrated into the genome of ahost cell upon introduction into the host cell, and thereby arereplicated along with the host genome. Moreover, certain vectors arecapable of directing the expression of genes to which they areoperatively linked. Such vectors are referred to herein as “recombinantexpression vectors” (or simply, “expression vectors”). Expressionvectors useful in recombinant DNA techniques include plasmids. As usedherein, “plasmid” and “vector” may be used interchangeably, as theplasmid is the most commonly used form of vector. However, also includedare other forms of expression vectors, such as viral vectors (e.g.,replication defective retroviruses, adenoviruses and adeno-associatedviruses), which serve equivalent functions.

The term “host cell” or “recombinant host cell”, which are usedinterchangeably, refers to a cell that comprises a nucleic acid that isnot naturally present in the cell, and may be a cell into which arecombinant expression vector has been introduced. It should beunderstood that such terms refer not only to the particular subject cellbut to the progeny of such a cell. Because certain modifications mayoccur in succeeding generations due to either mutation or environmentalinfluences, such progeny may not, in fact, be identical to the parentcell, but are still included within the scope of the term “host cell” asused herein.

An “immune response” is a biological response in an organism againstforeign agents, e.g., antigens, that protects the organism against theseagents and diseases caused by them. An immune response is mediated bythe action of a cell of the immune system (for example, a T lymphocyte,B lymphocyte, natural killer (NK) cell, macrophage, eosinophil, mastcell, dendritic cell or neutrophil) and soluble macromolecules producedby any of these cells or the liver (including antibodies, cytokines, andcomplement) that results in selective targeting, binding to, damage to,destruction of, and/or elimination from the organism's body of invadingpathogens, cells or tissues infected with pathogens, cancerous or otherabnormal cells, or, in cases of autoimmunity or pathologicalinflammation, normal cells or tissues, including, for example, humancells or tissues. An immune reaction includes, e.g., activation orinhibition of a T cell, e.g., an effector T cell or a T helper (Th)cell, such as a CD4+ or CD8+ T cell, or the inhibition or depletion of aTreg cell. “Effector T” (“Teff”) cells are T cells (e.g., CD4+ and CD8+T cells) with cytolytic activities. T helper (Th) cells secretecytokines and activate and direct other immune cells, but does notinclude regulatory T cells (Treg cells). T regulatory (“Treg”) cells area subpopulation of T cells that modulate the immune system, maintaintolerance to self-antigens, and prevent autoimmune disease. Memory Bcells are a B cell sub-type that are formed within germinal centersfollowing primary infection and are important in generating anaccelerated and more robust antibody-mediated immune response in thecase of re-infection (also known as a secondary immune response). NKcells are a type of cytotoxic lymphocyte critical to the innate immunesystem. The role NK cells play is analogous to that of cytotoxic T cellsin the vertebrate adaptive immune response. NK cells provide rapidresponses to viral-infected cells and respond to tumor formation.

As used herein, the term “T cell-mediated response” refers to a responsemediated by T cells, e.g., effector T cells (e.g., CD8+ cells) andhelper T cells (e.g., CD4+ cells). T cell mediated responses include,for example, T cell cytotoxicity and proliferation.

As used herein, the term “cytotoxic T lymphocyte (CTL) response” refersto an immune response induced by cytotoxic T cells. CTL responses aremediated by, for example, CD8+ T cells.

An “immunomodulator” or “immunoregulator” refers to an agent, e.g., acomponent of a signaling pathway that may be involved in modulating,regulating, or modifying an immune response. “Modulating,” “regulating,”or “modifying” an immune response refers to any alteration in a cell ofthe immune system or in the activity of such cell (e.g., an effector Tcell, such as a Th1 cell). Such modulation includes stimulation orsuppression of the immune system, which may be manifested by an increaseor decrease in the number of various cell types, an increase or decreasein the activity of these cells, and/or any other changes that can occurwithin the immune system. Both inhibitory and stimulatoryimmunomodulators have been identified, some of which may have enhancedfunction in a tumor microenvironment. In some embodiments, theimmunomodulator is located on the surface of a T cell. An“immunomodulatory target” or “immunoregulatory target” is animmunomodulator that is targeted for binding by, and whose activity isaltered by the binding of, a substance, agent, moiety, compound ormolecule. Immunomodulatory targets include, for example, receptors onthe surface of a cell (“immunomodulatory receptors”) and receptorligands (“immunomodulatory ligands”).

“Immunotherapy” refers to the treatment of a subject afflicted with orat risk of contracting or suffering a recurrence of a disease by amethod comprising inducing, enhancing, suppressing or otherwisemodifying an immune response.

“Immunostimulating therapy” or “immunostimulatory therapy” refers to atherapy that results in increasing (inducing or enhancing) an immuneresponse in a subject for, e.g., treating cancer.

“Potentiating an endogenous immune response” means increasing theeffectiveness or potency of an existing immune response in a subject.This increase in effectiveness and potency may be achieved, for example,by overcoming mechanisms that suppress the endogenous host immuneresponse or by stimulating mechanisms that enhance the endogenous hostimmune response.

As used herein, the term “linked” refers to the association of two ormore molecules. The linkage can be covalent or non-covalent. The linkagealso can be genetic (i.e., recombinantly fused). Such linkages can beachieved using a wide variety of art recognized techniques, such aschemical conjugation and recombinant protein production.

As used herein, “administering” refers to the physical introduction of acomposition comprising a therapeutic agent, e.g., an anti-ICOS antibody,to a subject, using any of the various methods and delivery systemsknown to those skilled in the art. “Administering” includes, forexample, administration to a human patient by another, such as, forexample, one or more healthcare providers, and self-administration bythe human patient. Various routes of administration for antibodiesdescribed herein include intravenous, intraperitoneal, intramuscular,subcutaneous, spinal or other parenteral routes of administration, forexample by injection or infusion. The phrase “parenteral administration”as used herein means modes of administration other than enteral andtopical administration, such as by injection, and includes, withoutlimitation, intravenous, intraperitoneal, intramuscular, intraarterial,intrathecal, intralymphatic, intralesional, intracapsular, intraorbital,intracardiac, intradermal, transtracheal, subcutaneous, subcuticular,intraarticular, subcapsular, subarachnoid, intraspinal, epidural andintrasternal injection and infusion, as well as in vivo electroporation.Alternatively, an antibody described herein can be administered via anon-parenteral route, such as a topical, epidermal or mucosal route ofadministration, for example, intranasally, orally, vaginally, rectally,sublingually or topically. Administering can also be performed, forexample, once, a plurality of times, and/or over one or more extendedperiods.

As used herein, “adjunctive” or “combined” administration(coadministration) includes simultaneous administration of the compoundsin the same or different dosage form, or separate administration of thecompounds (e.g., sequential administration). Thus, a first antibody,e.g., the anti-ICOS antibody, and a second, third, or more antibodiescan be simultaneously administered in a single formulation.Alternatively, the first and second (or more) antibodies can beformulated for separate administration and are administered concurrentlyor sequentially. “Combination” therapy, as used herein, meansadministration of two or more therapeutic agents in a coordinatedfashion, and includes, but is not limited to, concurrent dosing.Specifically, combination therapy encompasses both co-administration(e.g. administration of a co-formulation or simultaneous administrationof separate therapeutic compositions) and serial or sequentialadministration, provided that administration of one therapeutic agent isconditioned in some way on administration of another therapeutic agent.For example, one therapeutic agent may be administered only after adifferent therapeutic agent has been administered and allowed to act fora prescribed period of time. (See, e.g., Kohrt et al. (2011) Blood117:2423).

For example, the anti-ICOS antibody can be administered first followedby (e.g., immediately followed by) the administration of a secondantibody, or vice versa. In one embodiment, the anti-ICOS antibody isadministered prior to administration of the second antibody. In anotherembodiment, the anti-ICOS antibody is administered, for example, withinabout 30 minutes of the second antibody. Such concurrent or sequentialadministration preferably results in both antibodies beingsimultaneously present in treated patients.

As used herein, the terms “inhibits” or “blocks” are usedinterchangeably and encompass both partial and completeinhibition/blocking by at least about 50%, 60%, 70%, 80%, 90%, 95%, 99%,or 100%, as determined e.g., by methods described herein.

As used herein, “cancer” refers a broad group of diseases characterizedby the uncontrolled growth of abnormal cells in the body. Unregulatedcell growth or division may result in the formation of malignant tumorsor cells that invade neighboring tissues and may metastasize to distantparts of the body through the lymphatic system or bloodstream.

The terms “treat,” “treating,” and “treatment,” as used herein, refer toany type of intervention or process performed on, or administering anactive agent to, the subject with the objective of reversing,alleviating, ameliorating, inhibiting, or slowing down or preventing theprogression, development, severity or recurrence of a symptom,complication, condition or biochemical indicia associated with adisease. In contrast, “prophylaxis” or “prevention” refers toadministration to a subject who does not have a disease to prevent thedisease from occurring. “Treat,” “treating,” and “treatment” does notencompass prophylaxis or prevention.

The term “effective dose” or “effective dosage” is defined as an amountsufficient to achieve or at least partially achieve a desired effect. A“therapeutically effective amount” or “therapeutically effective dosage”of a drug or therapeutic agent is any amount of the drug that, when usedalone or in combination with another therapeutic agent, promotes diseaseregression evidenced by a decrease in severity of disease symptoms, anincrease in frequency and duration of disease symptom-free periods, or aprevention of impairment or disability due to the disease affliction. A“prophylactically effective amount” or a “prophylactically effectivedosage” of a drug is an amount of the drug that, when administered aloneor in combination with another therapeutic agent to a subject at risk ofdeveloping a disease or of suffering a recurrence of disease, preventsthe development or recurrence of the disease. The ability of atherapeutic agent to promote disease regression or of a prophylacticagent to prevent the development or recurrence of the disease can beevaluated using a variety of methods known to the skilled practitioner,such as in human subjects during clinical trials, in animal modelsystems predictive of efficacy in humans, or by assaying the activity ofthe agent in in vitro assays.

The administration of effective amounts of the anti-ICOS antibody alone,or anti-ICOS antibody combined with anti-PD-1 antibody, combined with ananti-PD-L1 antibody, or combined with anti-CTLA-4 antibody, according toany of the methods provided herein, can result in at least onetherapeutic effect, including, for example, reduced tumor growth orsize, reduced number of metastatic lesions appearing over time, completeremission, partial remission, or stable disease. For example, themethods of treatment produce a comparable clinical benefit rate(CBR=complete remission (CR)+partial remission (PR)+stable disease (SD)lasting ≥6 months) better than that achieved without administration ofthe anti-ICOS antibody, or than that achieved with administration of anyone of the combined antibodies, e.g., the improvement of clinicalbenefit rate is about 20% 20%, 30%, 40%, 50%, 60%, 70%, 80% or more.

By way of example, an anti-cancer agent is a drug that slows cancerprogression or promotes cancer regression in a subject. In someembodiments, a therapeutically effective amount of the drug promotescancer regression to the point of eliminating the cancer. “Promotingcancer regression” means that administering an effective amount of thedrug, alone or in combination with an anti-neoplastic agent, results ina reduction in tumor growth or size, necrosis of the tumor, a decreasein severity of at least one disease symptom, an increase in frequencyand duration of disease symptom-free periods, a prevention of impairmentor disability due to the disease affliction, or otherwise ameliorationof disease symptoms in the patient. “Pharmacological effectiveness,”“effectiveness,” or “efficacy” refers to the ability of the drug topromote cancer regression in the patient. “Physiological safety” refersto an acceptably low level of toxicity or other adverse physiologicaleffects at the cellular, organ and/or organism level (adverse effects)resulting from administration of the drug.

By way of example, for the treatment of tumors, a therapeuticallyeffective amount or dosage of the drug inhibits tumor cell growth by atleast about 20%, by at least about 30% by at least about 40%, by atleast about 50%, by at least about 60%, by at least above 70%, by atleast about 80% relative to untreated subjects, or by at least about90%. In some embodiments, a therapeutically effective amount or dosageof the drug completely inhibits cell growth or tumor growth, i.e.,inhibits cell growth or tumor growth by 100%. The ability of a compound,including an antibody, to inhibit tumor growth can be evaluated usingthe assays described herein. Alternatively, this property of acomposition can be evaluated by examining the ability of the compound toinhibit cell growth; such inhibition can be measured in vitro by assaysknown to the skilled practitioner. In some embodiments, inhibition oftumor growth may not be immediate after treatment, and may only occurafter a period of time or after repeated administration. In otherembodiments described herein, tumor regression is observed and continuesfor at least about 20 days, at least about 30 days, at least about 40days, at least about 50 days, or at least about 60 days, or longer.

As used herein, the terms “fixed dose”, “flat dose” and “flat-fixeddose” are used interchangeably and refer to a dose that is administeredto a patient without regard for the weight or body surface area of thepatient. The fixed or flat dose is therefore not provided as a mg/kgdose, but rather as an absolute amount of the therapeutic agent.

As used herein, the term “weight based” dose or dosing means that a doseadministered to a patient is calculated based on the patient's weight.For example, when a 60 kg patient requires 3 mg/kg of an anti-ICOSantibody, one can calculate and use the appropriate amount of theanti-ICOS antibody (i.e., 180 mg) for administration.

The term “patient” includes human and other mammalian subjects thatreceive either therapeutic or prophylactic treatment.

The term “subject” includes any human or non-human animal. For example,the methods and compositions herein disclosed can be used to treat asubject having cancer. A non-human animal includes all vertebrates,e.g., mammals and non-mammals, including non-human primates, sheep,dogs, cows, chickens, amphibians, reptiles, etc. In one embodiment, thesubject is a human subject.

As used herein, the term “a” or “an” entity refers to one or more ofthat entity unless otherwise specified; for example, “a nucleotidesequence,” is understood to represent one or more nucleotide sequences.As such, the terms “a” or “an”, “one or more,” and “at least one” can beused interchangeably herein.

As used herein, “and/or” is to be taken as specific disclosure of eachof the two specified features or components with or without the other.Thus, the term “and/or” as used in a phrase such as “A and/or B”includes “A and B,” “A or B,” “A” alone, and “B” alone. Likewise, theterm “and/or” as used in a phrase such as “A, B, and/or C” encompasseseach of the following: A, B, and C; A, B, or C; A or C; A or B; B or C;A and C; A and B; B and C; A alone; B alone; and C alone.

It is understood that wherever aspects are described herein with thelanguage “comprising,” otherwise analogous aspects described in terms of“consisting of” and/or “consisting essentially of” are also provided.

Units, prefixes, and symbols are denoted in their Système Internationalde Unites (SI) accepted form. Numeric ranges are inclusive of thenumbers defining the range. Unless otherwise indicated, nucleotidesequences are written left to right in 5′ to 3′ orientation. Amino acidsequences are written left to right in amino to carboxy orientation.

As used herein, the term “about” means approximately, roughly, around,or in the region of. When the term “about” is used in conjunction with anumerical range, it modifies that range by extending the boundariesabove and below the numerical values set forth. In general, the term“about” can modify a numerical value above and below the stated value bya variance of, e.g., 10 percent, up or down (higher or lower).

The headings provided herein are not limitations of the various aspectsof the disclosure, and should be read by reference to the specificationas a whole. Accordingly, the terms defined immediately below are morefully defined by reference to the specification in its entirety. Variousaspects described herein are described in further detail in thefollowing subsections.

I. Anti-ICOS Antibodies

The present invention discloses, in some embodiments, antibodies, suchas fully human antibodies, with desirable functions or properties.Described herein are agonistic anti-human ICOS (anti-huICOS) antibodieshaving desirable properties for use as therapeutic agents in treatingdiseases such as cancers. These properties include one or more of theability to bind to human ICOS with high affinity, acceptably lowimmunogenicity in human subjects, the ability to bind preferentially toFcγRIIb (a specific type of IgG Fc receptor), and the absence ofsequence liabilities that reduce the chemical stability of the antibody.The antibodies of the invention are also useful, e.g., for diagnosis ofcancer and other disorders associated with ICOS expression and/oractivity.

The anti-ICOS antibodies disclosed herein by amino acid sequence bind tospecific epitopes on human ICOS, as described in the Examples.

Anti-huICOS Antibodies Having Particular Functional Properties

The antibodies of the invention are characterized by particularfunctional features or properties. For example, the antibodiesspecifically bind to human ICOS with high affinity. In some embodiments,the antibodies specifically bind to the site on ICOS to which ICOS-Lbinds. Binding to human ICOS can be assessed using one or moretechniques well established in the art. For example, in someembodiments, the antibody can be tested by a flow cytometry assay inwhich the antibody is reacted with a cell line that expresses humanICOS, such as CHO cells that have been transfected to express human ICOSon their cell surface. Additionally or alternatively, the binding of theantibody, including the binding kinetics (e.g., K_(D) value) can betested in Biacore binding assays. Still other suitable binding assaysinclude ELISA assays using, for example, a recombinant human ICOSprotein.

In one embodiment, the antibody, or antigen-binding portion thereof, ofthe invention binds to an ICOS protein with a K_(D) of 5×10⁻⁸ M or less,binds to an ICOS protein with a K_(D) of 2×10⁻⁸ M or less, binds to anICOS protein with a K_(D) of 5×10⁻⁹ M or less, binds to an ICOS proteinwith a K_(D) of 4×10⁻⁹ M or less, binds to an ICOS protein with a K_(D)of 3×10⁻⁹M or less, binds to an ICOS protein with a K_(D) of 2×10⁻⁹ M orless, binds to an ICOS protein with a K_(D) of 1×10⁻⁹ M or less, bindsto an ICOS protein with a K_(D) of 5×10⁻¹⁰ M or less, or binds to anICOS protein with a K_(D) of 1×10⁻¹⁰ M or less.

In another embodiment, the antibody binds one or more residues ofSIFDPPPFKVTL (SEQ ID NO: 203) of human ICOS. In another embodiment, theantibody binds to an epitope which comprises amino acid residuesSIFDPPPFKVTL (SEQ ID NO: 203) of human ICOS. In another embodiment, theantigen-binding portion of the antibody binds to an epitope whichcomprises amino acid residues SIFDPPPFKVTL (SEQ ID NO: 203) of humanICOS.

In another embodiment, the antibody binds to human ICOS and stimulatesan immune response, e.g., an antigen-specific T cell response. Theability of the antibody to stimulate an immune response can be tested bymeasuring tumor growth, such as in an in vivo tumor graft model (see,e.g., Examples 6, 7, 8, and 9).

In another embodiment, the antibody, or antigen-binding portion thereof,binds to human ICOS and exhibits at least one of the followingproperties:

-   -   (a) binding to one or more residues within SIFDPPPFKVTL (SEQ ID        NO: 203) of human ICOS;    -   (b) binding to the same epitope on human ICOS as antibody        ICOS.33, 17C4, 9D5, 3E8, 1D7, or 2644;    -   (c) competing for binding to human ICOS with antibody ICOS.33,        17C4, 9D5, 3E8, 1D7, or 2644;    -   (d) reducing ADCC activity compared to an IgG1 control antibody;    -   (e) increasing specificity for binding to FcγRIIb receptor;    -   (f) blocking binding of an ICOS ligand (ICOS-L) to human ICOS;    -   (g) blocking the interaction of human ICOS and human ICOS-L;    -   (h) binding to human, cynomolgus, mouse, and rat ICOS;    -   (i) binding to activated human and cynomolgus T cells;    -   (j) binds to human T cells with an EC50 of about 0.7 nM and        cynomolgus T cells with an EC50 of about 0.3 nM;    -   (k) no binding to human CD28 or human CTLA-4;    -   (l) activating at least one primary T lymphocyte, such as a CD4+        Teff cell, a Tfh cell, and a Treg cell;    -   (m) induces proliferation and interferon-gamma (IFN-γ)        production in CD25− CD4+ T cells with an EC50 of about 0.01 to        about 0.16 nM in an in vitro CHO-OKT3-CD32A co-culture assay;    -   (n) inducing protein kinase B (pAkt) in an in vitro primary T        cell signaling assay with an EC50 of about 30 nM;    -   (o) induces IFN-γ production in CD25− CD4+ T cells with an EC50        of about 0.002 to about 0.4 nM in a staphylococcal enterotoxin B        in a CD25− CD4+ T cell and B cell co-culture assay.    -   (p) inducing interleukin 10 (IL-10) production in response to        staphylococcal enterotoxin B in a Tfh and naive B cell        co-culture assay;    -   (q) inducing a greater proliferation increase of CD3-stimulated        Teffs compared to CD45RA+ Tregs and CD45RO+ Tregs in an in vitro        assay;    -   (r) increasing proliferation in Teffs compared to CD45RA+ Tregs        (e.g., wherein the proliferation increase is greater in CD45RA+        Tregs compared to CD45RO+ Tregs);    -   (s) reducing Teff suppression by Tregs;    -   (t) wherein about 10 μg/mL of the antibody does not increase        cytokine production in a whole blood cell assay;    -   (u) increasing secretion of at least one of IL-10 and IFN-g by        Tfh cells in vitro; and/or    -   (v) stimulating ICOS-mediated signaling.

In another embodiment, the isolated antibody is a humanized isolatedantibody (or antigen binding portion thereof) that binds to human ICOSand blocks the binding and/or the interaction of an ICOS ligand (e.g.,human ICOS-L) to human ICOS and induces proliferation andinterferon-gamma (IFN-γ) production in CD25− CD4+ T cells with an EC50of about 0.083 nM in an in vitro CHO-OKT3-CD32A co-culture assay. Inanother embodiment, the isolated antibody is a humanized isolatedantibody (or antigen binding portion thereof) that binds to human ICOSand blocks the binding and/or the interaction of an ICOS ligand (e.g.,human ICOS-L) to human ICOS and induces proliferation andinterferon-gamma (IFN-γ) production in CD25− CD4+ T cells with an EC50of about 0.01 to about 0.1 nM in an in vitro CHO-OKT3-CD32A co-cultureassay.

In one aspect, the isolated antibody is a humanized isolated antibody(or antigen binding portion thereof) that binds to human ICOS and blocksthe binding and/or the interaction of an ICOS ligand (e.g., humanICOS-L) to human ICOS and induces IFN-γ production in CD25− CD4+ T cellswith an EC50 of about 0.2 nM in a staphylococcal enterotoxin B in aCD25− CD4+ T cell and B cell co-culture assay. In another aspect, theisolated antibody is a humanized isolated antibody (or antigen bindingportion thereof) that binds to human ICOS and blocks the binding and/orthe interaction of an ICOS ligand (e.g., human ICOS-L) to human ICOS andinduces IFN-γ production in CD25− CD4+ T cells with an EC50 of about0.01-0.1 nM in a staphylococcal enterotoxin B in a CD25− CD4+ T cell andB cell co-culture assay.

In some embodiments, antibodies of the invention include humanized andfully human monoclonal antibodies. In other embodiments, the antibodiesare, for example, chimeric monoclonal antibodies.

Monoclonal Antibodies ICOS.33 IgG1f S267E, 17C4, 9D5, 3E8, 1D7, and 2644

In some embodiments, the antibodies of the invention are the humanizedand human monoclonal antibodies ICOS.33 IgG1f S267E, 17C4, 9D5, 3E8,1D7, and 2644, which are isolated and structurally characterized asdescribed in the following Examples. The V_(H) amino acid sequences ofICOS.33 IgG1f S267E, 17C4, 9D5, 3E8, 1D7, and 2644 and the V_(L) aminoacid sequences of ICOS.33 IgG1f S267E, 17C4, 9D5, 3E8, 1D7, and 2644 areset forth in Table 35.

Given that each of these antibodies can bind to human ICOS, the V_(H)and V_(L) sequences can be “mixed and matched” to create otheranti-huICOS binding molecules of the invention. In some embodiments,when V_(H) and V_(L) chains are mixed and matched, a V_(H) sequence froma particular V_(H)/V_(L) pairing is replaced with a structurally similarV_(H) sequence. Likewise, in some embodiments, a V_(L) sequence from aparticular V_(H)/V_(L) pairing is replaced with a structurally similarV_(L) sequence.

Accordingly, in one aspect, this disclosure provides an isolatedmonoclonal antibody, or antigen binding portion thereof, comprising:

(a) a heavy chain variable region comprising an amino acid sequence setforth in SEQ ID NOs: 5, 16, 24, 32, 40, or 186; and

(b) a light chain variable region comprising an amino acid sequence setforth in SEQ ID NOs: 6, 17, 25, 33, 41, 48, or 189;

wherein the antibody specifically binds human ICOS.

In some embodiments, heavy and light chain variable region combinationsinclude:

(a) a heavy chain variable region comprising the amino acid sequence ofSEQ ID NO: 5 and a light chain variable region comprising the amino acidsequence of SEQ ID NO: 6;

(b) a heavy chain variable region comprising the amino acid sequence ofSEQ ID NO: 16 and a light chain variable region comprising the aminoacid sequence of SEQ ID NO: 17;

(c) a heavy chain variable region comprising the amino acid sequence ofSEQ ID NO: 24 and a light chain variable region comprising the aminoacid sequence of SEQ ID NO: 25;

(d) a heavy chain variable region comprising the amino acid sequence ofSEQ ID NO: 32 and a light chain variable region comprising the aminoacid sequence of SEQ ID NO: 33;

(e) a heavy chain variable region comprising the amino acid sequence ofSEQ ID NO: 40 and a light chain variable region comprising the aminoacid sequence of SEQ ID NO: 41;

(f) a heavy chain variable region comprising the amino acid sequence ofSEQ ID NO: 40 and a light chain variable region comprising the aminoacid sequence of SEQ ID NO: 48; or

(g) a heavy chain variable region comprising the amino acid sequence ofSEQ ID NO: 186 and a light chain variable region comprising the aminoacid sequence of SEQ ID NO: 189.

In another aspect, this disclosure provides antibodies that comprise theheavy chain and light chain CDR1s, CDR2s and CDR3s of ICOS.33 IgG1fS267E, 17C4, 9D5, 3E8, 1D7, and 2644, or combinations thereof. The aminoacid sequences of the V_(H) CDR1s of ICOS.33 IgG1f S267E, 17C4, 9D5,3E8, 1D7, and 2644 are shown in SEQ ID NOs: 9, 18, 26, 34, 42, and 191,respectively. The amino acid sequences of the V_(H) CDR2s of ICOS.33IgG1f S267E, 17C4, 9D5, 3E8, 1D7, and 2644 are shown in SEQ ID NOs: 10,19, 27, 35, 43, and 192, respectively. The amino acid sequences of theV_(H) CDR3s of ICOS.33 IgG1f S267E, 17C4, 9D5, 3E8, 1D7, and 2644 areshown in SEQ ID NOs: 11, 20, 28, 36, 44, and 193, respectively. Theamino acid sequences of the V_(L) CDR1s of ICOS.33 IgG1f S267E, 17C4,9D5, 3E8, 1D7, and 2644 are shown in SEQ ID NOs: 12, 21, 29, 37, 49, and194, respectively. The amino acid sequences of the V_(L) CDR2s ofICOS.33 IgG1f S267E, 17C4, 9D5, 3E8, 1D7, and 2644 are shown in SEQ IDNOs: 14, 22, 30, 38, 50, and 195, respectively. The amino acid sequencesof the V_(L) CDR3s of ICOS.33 IgG1f S267E, 17C4, 9D5, 3E8, 1D7, and 2644are shown in SEQ ID NOs: 15, 23, 31, 39, 51, and 196, respectively. TheCDR regions are delineated using the Kabat system (Kabat et al., 1991)Sequences of Proteins of Immunological Interest, Fifth Edition, U.S.Department of Health and Human Services, NIH Publication No. 91-3242).

Given that each of these antibodies can bind to human ICOS and thatantigen-binding specificity is provided primarily by the CDR1, CDR2, andCDR3 regions, the V_(H) CDR1, CDR2, and CDR3 sequences and V_(L) CDR1,CDR2, and CDR3 sequences can be “mixed and matched” (i.e., CDRs fromdifferent antibodies can be mixed and matched, although each antibodymust contain a V_(H) CDR1, CDR2, and CDR3 and a V_(L) CDR1, CDR2, andCDR3) to create other anti-huICOS binding molecules of the invention.ICOS binding of such “mixed and matched” antibodies can be tested usingthe binding assays described herein, including in the Examples (e.g.,ELISAs, Biacore® analysis). In some embodiments, when V_(H) CDRsequences are mixed and matched, the CDR1, CDR2 and/or CDR3 sequencefrom a particular V_(H) sequence is replaced with a structurally similarCDR sequence(s). Likewise, in some embodiments, when V_(L) CDR sequencesare mixed and matched, the CDR1, CDR2 and/or CDR3 sequence from aparticular V_(L) sequence preferably is replaced with a structurallysimilar CDR sequence(s). It will be readily apparent to the ordinarilyskilled artisan that novel V_(H) and V_(L) sequences can be created bysubstituting one or more V_(H) and/or V_(L) CDR region sequences withstructurally similar sequences from the CDR sequences disclosed hereinfor monoclonal antibodies ICOS.33 IgG1f S267E, 17C4, 9D5, 3E8, 1D7, and2644.

Accordingly, in another aspect, this disclosure provides an isolatedmonoclonal antibody, or antigen binding portion thereof comprising:

(a) a heavy chain variable region CDR1 comprising an amino acid sequenceset forth in SEQ ID NOs: 9, 18, 26, 34, 42, or 191;

(b) a heavy chain variable region CDR2 comprising an amino acid sequenceset forth in SEQ ID NOs: 10, 19, 27, 35, 43, or 192;

(c) a heavy chain variable region CDR3 comprising an amino acid sequenceoffset forth in SEQ ID NOs: 11, 20, 28, 36, 44, or 193;

(d) a light chain variable region CDR1 comprising an amino acid sequenceset forth in SEQ ID NOs: 12, 21, 29, 37, 49, or 194;

(e) a light chain variable region CDR2 comprising an amino acid sequenceset forth in SEQ ID NOs: 14, 22, 30, 38, 50, or 195; and

(f) a light chain variable region CDR3 comprising an amino acid sequenceset forth in SEQ ID NOs: 15, 23, 31, 39, 51, or 196;

-   -   wherein the antibody specifically binds human ICOS.        In one embodiment, the antibody comprises:

(a) a heavy chain variable region CDR1 comprising SEQ ID NO: 9;

(b) a heavy chain variable region CDR2 comprising SEQ ID NO: 10;

(c) a heavy chain variable region CDR3 comprising SEQ ID NO: 11;

(d) a light chain variable region CDR1 comprising SEQ ID NO: 12;

(e) a light chain variable region CDR2 comprising SEQ ID NO: 14; and

(f) a light chain variable region CDR3 comprising SEQ ID NO: 15.

In another embodiment, the antibody comprises:

(a) a heavy chain variable region CDR1 comprising SEQ ID NO: 18;

(b) a heavy chain variable region CDR2 comprising SEQ ID NO: 19;

(c) a heavy chain variable region CDR3 comprising SEQ ID NO: 20;

(d) a light chain variable region CDR1 comprising SEQ ID NO: 21;

(e) a light chain variable region CDR2 comprising SEQ ID NO: 22; and

(f) a light chain variable region CDR3 comprising SEQ ID NO: 23.

In another embodiment, the antibody comprises:

(a) a heavy chain variable region CDR1 comprising SEQ ID NO: 26;

(b) a heavy chain variable region CDR2 comprising SEQ ID NO: 27;

(c) a heavy chain variable region CDR3 comprising SEQ ID NO: 28;

(d) a light chain variable region CDR1 comprising SEQ ID NO: 29;

(e) a light chain variable region CDR2 comprising SEQ ID NO: 30; and

(f) a light chain variable region CDR3 comprising SEQ ID NO: 31.

In another embodiment, the antibody comprises:

(a) a heavy chain variable region CDR1 comprising SEQ ID NO: 34;

(b) a heavy chain variable region CDR2 comprising SEQ ID NO: 35;

(c) a heavy chain variable region CDR3 comprising SEQ ID NO: 36;

(d) a light chain variable region CDR1 comprising SEQ ID NO: 37;

(e) a light chain variable region CDR2 comprising SEQ ID NO: 38; and

(f) a light chain variable region CDR3 comprising SEQ ID NO: 39.

In another embodiment, the antibody comprises:

(a) a heavy chain variable region CDR1 comprising SEQ ID NO: 42;

(b) a heavy chain variable region CDR2 comprising SEQ ID NO: 43;

(c) a heavy chain variable region CDR3 comprising SEQ ID NO: 44;

(d) a light chain variable region CDR1 comprising SEQ ID NO: 49;

(e) a light chain variable region CDR2 comprising SEQ ID NO: 50; and

(f) a light chain variable region CDR3 comprising SEQ ID NO: 51.

In another embodiment, the antibody comprises:

(a) a heavy chain variable region CDR1 comprising SEQ ID NO: 191;

(b) a heavy chain variable region CDR2 comprising SEQ ID NO: 192;

(c) a heavy chain variable region CDR3 comprising SEQ ID NO: 193;

(d) a light chain variable region CDR1 comprising SEQ ID NO: 194;

(e) a light chain variable region CDR2 comprising SEQ ID NO: 195; and

(f) a light chain variable region CDR3 comprising SEQ ID NO: 196.

It is well known in the art that the CDR3 domain, independently from theCDR1 and/or CDR2 domain(s), alone can determine the binding specificityof an antibody for a cognate antigen and that multiple antibodies canpredictably be generated having the same binding specificity based on acommon CDR3 sequence. (See, e.g., Klimka et al., British J. of Cancer83(2):252-260 (2000). Accordingly, the present disclosure providesmonoclonal antibodies comprising one or more heavy and/or light chainCDR3 domains from an antibody derived from a human or non-human animal,wherein the monoclonal antibody is capable of specifically binding tohuman ICOS. In certain aspects, the present disclosure providesmonoclonal antibodies comprising one or more heavy and/or light chainCDR3 domain from a non-human antibody, such as a mouse or rat antibody,wherein the monoclonal antibody is capable of specifically binding tohuman ICOS. Within some embodiments, such inventive antibodiescomprising one or more heavy and/or light chain CDR3 domain from anon-human antibody (a) are capable of competing for binding with; (b)retain the functional characteristics; (c) bind to the same epitope;and/or (d) have a similar binding affinity as the corresponding parentalnon-human antibody.

In other aspects, the present disclosure provides monoclonal antibodiescomprising one or more heavy and/or light chain CDR3 domain from a humanantibody, such as, e.g., a human antibody obtained from a non-humananimal, wherein the human antibody is capable of specifically binding tohuman ICOS. In other aspects, the present disclosure provides monoclonalantibodies comprising one or more heavy and/or light chain CDR3 domainfrom a first human antibody, such as, for example, a human antibodyobtained from a non-human animal, wherein the first human antibody iscapable of specifically binding to human ICOS, and wherein the CDR3domain from the first human antibody replaces a CDR3 domain in a humanantibody that lacks binding specificity for ICOS to generate a secondhuman antibody that is capable of specifically binding to human ICOS. Insome embodiments, such inventive antibodies comprising one or more heavyand/or light chain CDR3 domain from the first human antibody (a) arecapable of competing for binding with; (b) retain the functionalcharacteristics; (c) bind to the same epitope; and/or (d) have a similarbinding affinity as the corresponding parental non-human antibody.

The present invention also provides anti-huICOS antibodies comprisingthe novel variable domain sequences disclosed herein and constantdomains with modified Fc regions having enhanced affinity for FcγRIIb ascompared with their affinity for other Fc receptors. In someembodiments, such agonistic anti-huICOS antibodies with enhancedFcγRIIb-specificity exhibit superior efficacy in treating cancer. Inother embodiments, such agonistic anti-huICOS antibodies with enhancedFcγRIIb-specificity exhibit superior efficacy in treating variousdisorders, e.g., cancer. Without intending to be limited by mechanistictheory, such FcγRIIb-specific agonistic anti-ICOS monoclonal antibodiesmay exhibit enhanced adjuvant effects by increasing the maturation ofdendritic cell, thus, promoting expansion and activation of cytotoxicCD8+ T cells, which leads to enhanced anti-tumor response. Withoutintending to be limited by theory, FcR-mediated signal enhancement ofagonist ICOS antibodies due to increased receptor clustering, or“cross-linking,” of the present invention may be a major contributor totherapeutic efficacy. Cross-linking of ICOS agonist antibodies by FcRengagement by the Fc portion of the antibody may increase signalstrength and thereby enhance cell activation.

The relative binding affinity of antibodies for activating (A) versusinhibitory (I) Fc receptors can be expressed as the “A/I” ratio, and istypically a function of the structure of the Fc region of an IgGantibody. See WO 2012/087928. Antibodies having enhanced specificity forbinding to inhibitory receptor FcγRIIb have lower A/I ratios. In someembodiments, the agonistic anti-huICOS antibodies described herein haveA/I ratios of less than 5, 4, 3, 2, 1, 0.5, 0.3, 0.1, 0.05, 0.03 or0.01.

Examples of human IgG1 constant domains comprising mutations to enhanceFcγRIIb specificity are described herein and are also provided in theSequence Listing. Sequence variants are defined with reference to humanIgG1f constant domain sequence provided at SEQ ID NO: 52 and shown inFIG. 2. The nomenclature regarding positions (numbering) of mutations inthe Fc region is according to the EU index as in Kabat et al., 1991)Sequences of Proteins of Immunological Interest, 5th Ed. Public HealthService, National Institutes of Health, Bethesda, Md.), whichfacilitates comparison of Fc sequences at equivalent positions inantibodies with differing variable domain lengths. See also Edelman etal. (1969) Proc. Nat'l Acad. Sci. (USA) 63:78; WO 2012/130831 (using thesame numbering system). Table 3 provides a summary of the Fc sequencevariants from which one of skill in the art could readily recognize thecorresponding positions in the antibody sequences disclosed herein. SEand SELF variants are described at Chu et al. (2008) Mol. Immunol.45:3926. P238D, V4, V7, V8, V9, V11 and V12 variants are described atMimoto et al. (2013) Protein Engineering Design & Selection 26:589 (e.g.at Table 1 therein).

TABLE 3 Fc Sequence Variants SEQ Designation ID: Sequence Variants IgG1f52 SE 53 S267E SELF 54 S267E L328F P238D 55 P238D V4 56 P238D P271G V4 -D270E 57 P238D P271G D270E V7 58 E233D P238D P271G A330R V8 59 G237DP238D H268D P271G V9 60 G237D P238D P271G A330R V9 - D270E 61 G237DP238D P271G A330R D270E V11 62 G237D P238D H268D P271G A330R V12 63E233D G237D P238D H268D P271G A330R

Additional Fc sequence variants with enhanced affinity for FcγRIIb aredisclosed at Yu et al. (2013) J. Am. Chem. Soc. 135:9723 (and WO2014/184545), including V262E and V264E, e.g. for use in combinationwith S267E and L328F.

Antibodies with Conservative Modifications

In certain embodiments, an antibody of the invention comprises a heavychain variable region comprising CDR1, CDR2, and CDR3 sequences and alight chain variable region comprising CDR1, CDR2, and CDR3 sequences,wherein one or more of these CDR sequences comprise specified amino acidsequences based on the antibodies described herein (e.g., ICOS.33 IgG1fS267E, 17C4, 9D5, 3E8, 1D7, and 2644), or conservative modificationsthereof, and wherein the antibodies retain the desired functionalproperties of the anti-huICOS antibodies of the invention. It isunderstood in the art that certain conservative sequence modificationscan be made that do not remove antigen binding. (See, e.g., Brummell etal. (1993) Biochem 32:1180-8). Accordingly, this disclosure provides anisolated monoclonal antibody, or antigen binding portion thereof,comprising a heavy chain variable region comprising CDR1, CDR2, and CDR3sequences and a light chain variable region comprising CDR1, CDR2, andCDR3 sequences, wherein:

(a) the heavy chain variable region comprising a CDR3 sequencecomprising an amino acid sequence set forth in SEQ ID NOs: 11, 20, 28,36, 44, or 193, or conservative modifications thereof;

(b) the light chain variable region comprising a CDR3 sequencecomprising an amino acid sequence set forth in SEQ ID NOs: 15, 23, 31,39, 51, or 196, or conservative modifications thereof; and

(c) the antibody, or antigen binding portion thereof, specifically bindshuman ICOS.

Additionally or alternatively, the antibody can possess one or more ofthe functional properties described herein, such as high affinitybinding to human ICOS, and/or the ability to stimulate antigen-specificT cell responses.

In some embodiments, the heavy chain variable region comprising a CDR2sequence comprises an amino acid sequence set forth in SEQ ID NOs: 10,19, 27, 35, 43, or 192, or conservative modifications thereof, and thelight chain variable region comprising a CDR2 sequence comprising anamino acid sequence set forth in SEQ ID NOs: 14, 22, 30, 38, 50, or 195,or conservative modifications thereof. In another embodiment, the heavychain variable region comprises a CDR1 sequence comprising an amino acidsequence set forth in SEQ ID NOs: 9, 18, 26, 34, 42, or 191, orconservative modifications thereof; and the light chain variable regioncomprising a CDR1 sequence comprising an amino acid sequence set forthin SEQ ID NOs: 12, 21, 29, 37, 49, or 194, or conservative modificationsthereof.

In various embodiments, the antibody can be, for example, humanantibodies, humanized antibodies, or chimeric antibodies.

Antibodies that Bind to the Same Epitope as Anti-huICOS Antibodies

In another embodiment, this disclosure provides antibodies that bind tothe same epitope on human ICOS as any of the anti-huICOS monoclonalantibodies of the invention (i.e., antibodies that have the ability tocross-compete for binding to human ICOS with any of the monoclonalantibodies of the invention). In some embodiments, the referenceantibody for cross-competition studies are the monoclonal antibodiesICOS.33 IgG1f S267E, 17C4, 9D5, 3E8, 1D7, and 2644.

Such cross-competing antibodies can be identified based on their abilityto cross-compete with ICOS.33 IgG1f S267E, 17C4, 9D5, 3E8, 1D7, and/or2644 in standard human ICOS binding assays. For example, standard ELISAassays can be used in which a recombinant human ICOS protein isimmobilized on the plate, one of the antibodies is fluorescentlylabeled, and the ability of non-labeled antibodies to compete off thebinding of the labeled antibody is evaluated. Additionally oralternatively, Biacore analysis can be used to assess the antibodies'ability to cross-compete. The ability of a test antibody to inhibit thebinding of, for example, ICOS.33 IgG1f S267E, 17C4, 9D5, 3E8, 1D7,and/or 2644, to human ICOS demonstrates that the test antibody cancompete with ICOS.33 IgG1f S267E, 17C4, 9D5, 3E8, 1D7, and/or 2644 forbinding to human ICOS and thus binds to the same epitope on human ICOSas ICOS.33 IgG1f S267E, 17C4, 9D5, 3E8, 1D7, and/or 2644. In oneembodiment, the antibody that binds to the same epitope on human ICOS asICOS.33 IgG1f S267E, 17C4, 9D5, 3E8, 1D7, and/or 2644 is a humanized orhuman monoclonal antibody.

As discussed further in Example 16, the binding of ICOS.33 IgG1f S267E,3E8, and 9D5 human ICOS has been mapped to residues 112-123 of ICOS (SEQID NO: 1), or the amino acid sequence SIFDPPPFKVTL (SEQ ID NO: 203).Accordingly, in one embodiment, the invention provides an anti-huICOSantibody that binds to one or more residues of SIFDPPPFKVTL (SEQ ID NO:203) of human ICOS, e.g., as determined by HDX-MS. In anotherembodiment, the anti-huICOS antibody binds to an epitope comprisingamino acid residues SIFDPPPFKVTL (SEQ ID NO: 203) of human ICOS.

Such humanized or human monoclonal antibodies can be prepared andisolated as described herein. For example, anti-huICOS antibodies thatbind to the same or similar epitopes to the antibodies disclosed hereinmay be raised using immunization protocols, e.g., those describedherein. The resulting antibodies can be screened for high affinitybinding to human ICOS. Selected antibodies can then be studied, e.g., inyeast display assay in which sequence variants of huICOS are presentedon the surface of yeast cells, or by hydrogen-deuterium exchangeexperiments, to determine the precise epitope bound by the antibody.

Epitope determinations may be made by any method known in the art. Insome embodiments, anti-huICOS antibodies are considered to bind to thesame epitope as an anti-huICOS mAb disclosed herein if they make contactwith one or more of the same residues within at least one region ofhuICOS; if they make contacts with a majority of the residues within atleast one region of huICOS; if they make contacts with a majority of theresidues within each region of huICOS; if they make contact with amajority of contacts along the entire length of huICOS; if they makecontacts within all of the same distinct regions of human ICOS; if theymake contact with all of the residues at any one region on human ICOS;or if they make contact with all of the same residues at all of the sameregions. Epitope “regions” are clusters of residues along, but notnecessarily directly adjacent within, the primary sequence.

Techniques for determining antibodies that bind to the “same epitope onhuICOS” with the antibodies described herein include x-ray analyses ofcrystals of antigen:antibody complexes, which provides atomic resolutionof the epitope. Other methods monitor the binding of the antibody toantigen fragments or mutated variations of the antigen where loss ofbinding due to an amino acid modification within the antigen sequenceindicates the epitope component. Methods may also rely on the ability ofan antibody of interest to affinity isolate specific short peptides(either in native three dimensional form or in denatured form) fromcombinatorial phage display peptide libraries or from a protease digestof the target protein. The peptides are then regarded as leads for thedefinition of the epitope corresponding to the antibody used to screenthe peptide library. For epitope mapping, computational algorithms havealso been developed that have been shown to map conformationaldiscontinuous epitopes.

The epitope or region comprising the epitope can also be identified byscreening for binding to a series of overlapping peptides spanning ICOS.Alternatively, the method of Jespers et al. (1994) Biotechnology 12:899may be used to guide the selection of antibodies having the same epitopeand therefore similar properties to the anti-ICOS antibodies describedherein. Using phage display, first, the heavy chain of the anti-ICOSantibody is paired with a repertoire of (e.g., human) light chains toselect an ICOS-binding antibody, and then the new light chain is pairedwith a repertoire of (e.g., human) heavy chains to select a (e.g.,human) ICOS-binding antibody having the same epitope or epitope regionas an anti-huICOS antibody described herein. Alternatively, variants ofan antibody described herein can be obtained by mutagenesis of cDNAsequences encoding the heavy and light chains of the antibody.

Alanine scanning mutagenesis, as described by Cunningham & Wells (1989)Science 244: 1081, or some other form of point mutagenesis of amino acidresidues in ICOS (such as the yeast display method provided at Example16) may also be used to determine the functional epitope for ananti-ICOS antibody.

The epitope or epitope region (an “epitope region” is a regioncomprising the epitope or overlapping with the epitope) bound by aspecific antibody may also be determined by assessing binding of theantibody to peptides comprising ICOS fragments. A series of overlappingpeptides encompassing the ICOS sequence (e.g., human ICOS) may besynthesized and screened for binding, e.g. in a direct ELISA, acompetitive ELISA (where the peptide is assessed for its ability toprevent binding of an antibody to ICOS bound to a well of a microtiterplate), or on a chip. Such peptide screening methods may not be capableof detecting some discontinuous functional epitopes, i.e., functionalepitopes that involve amino acid residues that are not contiguous alongthe primary sequence of the ICOS polypeptide chain.

An epitope may also be identified by MS-based protein footprinting, suchas HDX-MS and Fast Photochemical Oxidation of Proteins (FPOP). HDX-MSmay be conducted, e.g., as further described at Wei et al. (2014) DrugDiscovery Today 19:95, the methods of which are specificallyincorporated by reference herein. FPOP may be conducted as described,e.g., in Hambley & Gross (2005) J. American Soc. Mass Spectrometry16:2057, the methods of which are specifically incorporated by referenceherein.

The epitope bound by anti-ICOS antibodies may also be determined bystructural methods, such as X-ray crystal structure determination (e.g.,WO2005/044853), molecular modeling and nuclear magnetic resonance (NMR)spectroscopy, including NMR determination of the H-D exchange rates oflabile amide hydrogens in ICOS when free and when bound in a complexwith an antibody of interest (Zinn-Justin et al. (1992) Biochemistry31:11335; Zinn-Justin et al. (1993) Biochemistry 32:6884).

Unless otherwise indicated, and with reference to the claims, theepitope bound by an antibody is the epitope as determined by HDX-MSmethods.

Anti-huICOS Antibodies Derived from Hamster Antibodies

Described herein are examples of chimeric and humanized antibodies thatcomprise CDRs and/or antibody heavy and/or light chain variable regionsthat were derived from hamster sequences. Chimeric or humanizedantibodies described herein can be prepared based on the sequence of amonoclonal antibody, e.g., mouse or hamster, prepared by various methodsknown in the art. DNA encoding the heavy and light chain immunoglobulinscan be obtained from a hybridoma of interest and engineered to containhuman immunoglobulin sequences using standard molecular biologytechniques. For example, to create a chimeric antibody, the variableregions of, e.g., a mouse or hamster antibody can be linked to humanconstant regions using methods known in the art (see e.g., U.S. Pat. No.4,816,567 to Cabilly et al.). To create a humanized antibody, the CDRregions can be inserted into a human framework using methods known inthe art (see e.g., U.S. Pat. No. 5,225,539 to Winter, and U.S. Pat. Nos.5,530,101; 5,585,089; 5,693,762 and 6,180,370 to Queen et al).

Anti-ICOS Antibodies that Bind with High Affinity

In some embodiments, the anti-huICOS antibodies of the present inventionbind to huICOS with high affinity, like the anti-huICOS antibodiesdisclosed herein, making them effective therapeutic agents. In variousembodiments, anti-huICOS antibodies of the present invention bind tohuICOS with a K_(D) of less than 10 nM, 5 nM, 2 nM, 1 nM, 300 pM or 100pM. In other embodiments, the anti-huICOS antibodies of the presentinvention bind to huICOS with a K_(D) between 2 nM and 100 pM. Standardassays to evaluate the binding ability of the antibodies toward huICOSinclude ELISAs, RIAs, Western blots, biolayer interferometry (BLI) andBIACORE® SPR analysis (see Example 10).

Anti-ICOS Antibody Sequence Variants

Anti-ICOS antibody sequence variants disclosed herein maintain thedesirable functional properties disclosed herein. The CDR regions aredelineated using the Kabat system (Kabat, et al., 1991). In someembodiments, the present invention further provides human or humanizedanti-huICOS antibodies comprising CDR sequences that are at least 70%,75%, 80%, 85%, 90%, or 95%, 96%, 97%, 98%, or 99% identical to the CDRsequences of the antibodies disclosed herein. The present invention alsoprovides anti-huICOS antibodies comprising heavy and/or light chainvariable domain sequences that are at least 70%, 75%, 80%, 85%, 90%,95%, 96%, 97%, 98%, or 99% identical to the heavy and/or light chainvariable domain sequences of the antibodies disclosed herein, as well asanti-huICOS antibodies comprising full-length heavy and/or light chainsequences that are at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%,or 99% identical to the heavy and/or light chain sequences of theantibodies disclosed herein.

II. Engineered and Modified Antibodies

V_(H) and V_(L) Regions

Also provided are engineered and modified antibodies that can beprepared using an antibody having one or more of the V_(H) and/or V_(L)sequences disclosed herein as starting material to engineer a modifiedantibody, which modified antibody may have altered properties from thestarting antibody. In some embodiments, an antibody as described hereinwas engineered by modifying one or more residues within one or bothvariable regions (i.e., V_(H) and/or V_(L)), for example, within one ormore CDR regions and/or within one or more framework regions.Additionally or alternatively, an antibody as described herein wasengineered by modifying residues within the constant region(s), forexample, to alter the effector function(s) of the antibody.

In one embodiment, the variable region engineering includes CDRgrafting. Such grafting is of particular use in humanizing non-humananti-ICOS antibodies, e.g., anti-huICOS antibodies that compete forbinding with the anti-huICOS antibodies disclosed herein and/or bind tothe same epitope as the select anti-huICOS antibodies disclosed herein.Antibodies interact with target antigens predominantly through aminoacid residues that are located in the heavy and light chain CDRs. TheCDRs are hypervariable in sequence and/or form structurally definedloops (“hypervariable loops”). Expression vectors can be constructedsuch that they include CDR sequences from a specific reference (alsocalled “parental”) antibody grafted onto framework sequences from adifferent antibody (see, e.g., Riechmann, L. et al. (1998) Nature332:323-327; Jones, P. et al. (1986) Nature 321:522-525; Queen, C. etal. (1989) Proc. Natl. Acad. See. U.S.A. 86:10029-10033; U.S. Pat. No.5,225,539 to Winter, and U.S. Pat. Nos. 5,530,101; 5,585,089; 5,693,762and 6,180,370 to Queen et al.). In some instances, the resultingrecombinant antibody has properties that are similar to the parentalantibody. The engineered antibody can then be further modified toacquire properties that are distinct from the parental antibody. Inother instances, grafting the parental CDR sequences onto a frameworkabrogates certain characteristics of the parental antibody such that therecombinant antibody no longer has these characteristics. One exemplarycharacteristic is binding affinity with respect to an antigen. In suchinstances, it might be advantageous to further modify the engineeredantibody to regain the desired characteristics of the parental antibody.

Such framework sequences can be obtained from public DNA databases orpublished references that include germline antibody gene sequences. Forexample, germline DNA sequences for human heavy and light chain variableregion genes can be found in the “VBase” human germline sequencedatabase, as well as in Kabat, E. A., et al., 1991); Tomlinson, I. M.,et al. (1992) “The Repertoire of Human Germline V_(H) Sequences Revealsabout Fifty Groups of V_(H) Segments with Different Hypervariable Loops”J. Mol. Biol. 227:776-798; and Cox, J. P. L. et al. (1994) “A Directoryof Human Germ-line V_(H) Segments Reveals a Strong Bias in their Usage,”Eur. J. Immunol. 24:827-836; the contents of each of which are expresslyincorporated herein by reference.

In some embodiments, framework sequences for use in the antibodiesdescribed herein are those that are structurally similar to theframework sequences used by antibodies described herein. The V_(H) CDR1,2, and 3 sequences and the V_(L) CDR1, 2, and 3 sequences can be graftedonto framework regions that have the identical sequence as that found inthe germline immunoglobulin gene from which the framework sequencederive, or the CDR sequences can be grafted onto framework regions thatcontain up to 20 amino acid substitutions, including conservative aminoacid substitutions, as compared to the germline sequences. For example,it has been found that in certain instances, it is beneficial to mutateresidues within the framework regions to maintain or enhance the antigenbinding ability of the antibody (see e.g., U.S. Pat. Nos. 5,530,101;5,585,089; 5,693,762 and 6,180,370 to Queen et al).

Engineered antibodies described herein include those in whichmodifications have been made to framework residues within V_(H) and/orV_(L), e.g., to improve the properties of the antibody, such as todecrease the immunogenicity of the antibody. For example, one approachis to “back-mutate” one or more framework residues to the correspondinggermline sequence. More specifically, an antibody that has undergonesomatic mutation may contain framework residues that differ from thegermline sequence from which the antibody is derived. Such residues canbe identified by comparing the antibody framework sequences to thegermline sequences from which the antibody is derived. To return theframework region sequences to their germline configuration, the somaticmutations can be “back-mutated” to the germline sequence by, forexample, site-directed mutagenesis or PCR-mediated mutagenesis. Such“back-mutated” antibodies are also encompassed in this disclosure.

Another type of framework modification involves mutating one or moreresidues within the framework region, or even within one or more CDRregions, to remove T cell epitopes to thereby reduce the potentialimmunogenicity of the antibody. This approach is also referred to as“de-immunization” and is described in further detail in U.S. PatentPublication No. 20030153043 by Carr et al.

Another type of variable region modification is to mutate amino acidresidues within the CDR regions to improve one or more bindingproperties (e.g., affinity) of the antibody of interest. Site-directedmutagenesis or PCR-mediated mutagenesis can be performed to introducethe mutation(s) and the effect on antibody binding, or other functionalproperty of interest. Preferably, conservative modifications areintroduced. The mutations may be amino acid additions, deletions, orsubstitutions. In some embodiments, no more than one, two, three, fouror five residues within a CDR region are altered.

Methionine residues in CDRs of antibodies can be oxidized, resulting inpotential chemical degradation and consequent reduction in antibodypotency. Accordingly, also provided herein are anti-ICOS antibodies thathave one or more methionine residues in the heavy and/or light chainCDRs replaced with amino acid residues that do not undergo oxidativedegradation. Similarly, deamidation sites may be removed from anti-ICOSantibodies, particularly in the CDRs. Also provided herein areantibodies in which potential glycosylation sites within the antigenbinding domain were eliminated to prevent glycosylation that mayinterfere with antigen binding. See, e.g., U.S. Pat. No. 5,714,350.

Antibody Masking

In some embodiments, the antibodies disclosed herein are modified tolimit their binding to specific cells and/or tissue. In one embodiment,such antibodies comprise a blocking peptide “mask” that specificallybinds to the antigen binding surface of the antibody and interferes withantigen binding. In some embodiments, the mask is linked to each of thebinding arms of the antibody by a protease cleavable linker. See, e.g.,U.S. Pat. No. 8,518,404 to CytomX. Antibodies with protease cleavablelinkers are useful for treatment of cancers in which protease levels aregreatly increased in the tumor microenvironment compared with non-tumortissues. Selective cleavage of the cleavable linker in the tumormicroenvironment allows disassociation of the masking/blocking peptide,enabling antigen binding selectively in the tumor, rather than inperipheral tissues in which antigen binding might cause unwanted sideeffects.

In another embodiment, a bivalent binding compound (“masking ligand”)comprising two antigen binding domains is developed that binds to bothantigen binding surfaces of the (bivalent) antibody and interferes withantigen binding. In one embodiment, the two binding domain masks arelinked to each other (but not the antibody) by a cleavable linker, forexample, cleavable by a peptidase. (See, e.g., WO 2010/077643 toTegopharm Corp). Masking ligands may comprise, or be derived from, theantigen to which the antibody is intended to bind, or may beindependently generated (e.g., anti-idiotype binding fragments). Suchmasking ligands are useful for treatment of cancers in which proteaselevels are greatly increased in the tumor microenvironment compared withnon-tumor tissues. Selective cleavage of the cleavable linker in thetumor microenvironment allows disassociation of the two binding domainsfrom each other, reducing the avidity for the antigen-binding surfacesof the antibody. The resulting dissociation of the masking ligand fromthe antibody enables antigen binding selectively in the tumor, ratherthan in peripheral tissues in which antigen binding might cause unwantedside effects.

Fcs and Modified Fc Regions

In one embodiment, the antibodies described herein may comprise Fcregions selected based on the biological activities of the antibody.Salfeld (2007) Nat. Biotechnol. 25:1369. Human IgGs, for example, can beclassified into four subclasses, IgG1, IgG2, IgG3, and IgG4. Each ofthese subclasses comprise an Fc region having a unique profile forbinding to one or more of Fcγ receptors (activating receptors FcγRI(CD64), FcγRIIA, FcγRIIC (CD32a,c); FcγRIIIA and FcγRIIIB (CD16a,b) andinhibiting receptor FcγRIIB (CD32b), and for the first component ofcomplement (C1q). Human IgG1 and IgG3 bind to all Fcγ receptors; IgG2binds to FcγRIIA_(H131), and with lower affinity to FcγRIIA_(R131)FcγRIIIA_(V158); IgG4 binds to FcγRI, FcγRIIA, FcγRIIB, FcγRIIC, andFcγRIIIA_(V158); and the inhibitory receptor FcγRIIB has a loweraffinity for IgG1, IgG2 and IgG3 than all other Fcγ receptors. (Bruhnset al. (2009) Blood 113:3716). Studies have shown that FcγRI does notbind to IgG2, and FcγRIIIB does not bind to IgG2 or IgG4. Id. Ingeneral, with regard to ADCC activity, human IgG1≥IgG3>>IgG4≥IgG2. Insome embodiments, an IgG1 constant domain, rather than an IgG2 or IgG4,is chosen, e.g., for use in a therapeutic composition because ADCC isdesired. In other embodiments, IgG3 is chosen because activation ofFcγRIIIA-expressing NK cells, monocytes or macrophages is desirable. Inother embodiments, IgG4 is chosen because the antibody is used todesensitize allergy patients. IgG4 is also selected so that the antibodylacks all effector function.

Anti-huICOS antibody variable regions described herein may be linked(e.g., covalently linked or fused) to an Fc, e.g., an IgG1, IgG2, IgG3or IgG4 Fc, which may be of any allotype or isoallotype, e.g., for IgG1:G1m, G1m1(a), G1m2(x), G1m3(f), G1m17(z); for IgG2: G2m, G2m23(n); forIgG3: G3m, G3m21(g1), G3m28(g5), G3m11(b0), G3m5(b1), G3m13(b3),G3m14(b4), G3m10(b5), G3m15(s), G3m16(t), G3m6(c3), G3m24(c5), G3m26(u),G3m27(v). (See, e.g., Jefferis et al. (2009) mAbs 1:1). Selection ofallotype may be influenced by the potential immunogenicity concerns,e.g. to minimize the formation of anti-drug antibodies.

In some embodiments, anti-ICOS antibodies of the present invention havean Fc region that binds to or has enhanced binding to FcγRIIb, whichprovides enhanced agonism. See, e.g., WO 2012/087928; Li & Ravetch(2011) Science 333:1030; Wilson et al. (2011) Cancer Cell 19:101; Whiteet al. (2011) J. Immunol. 187:1754. In some embodiments, variableregions described herein may be linked to Fc variants that enhanceaffinity for the inhibitory receptor FcγRIIb, e.g., to enhanceapoptosis-inducing or adjuvant activity. Li & Ravetch (2012) Proc. Nat'lAcad. Sci. (USA) 109:10966; U.S. Pat. App. Pub. 2014/0010812. Suchvariants provides an antibody with immunomodulatory activities relatedto FcγRIIb+ cells, including, for example, B cells and monocytes. In oneembodiment, the Fc variants provide selectively enhanced affinity toFcγRIIb relative to one or more activating receptors. Such variants mayalso exhibit enhanced FcR-mediated cross-linking, resulting in enhancedtherapeutic efficacy. Modifications for altering binding to FcγRIIbinclude one or more modifications at, for example, positions 234, 235,236, 237, 239, 266, 267, 268, 325, 326, 327, 328, or 332, according tothe EU index. Exemplary substitutions for enhancing FcγRIIb affinityinclude but are not limited to 234D, 234E, 234F, 234W, 235D, 235F, 235R,235Y, 236D, 236N, 237D, 237N, 239D, 239E, 266M, 267D, 267E, 268D, 268E,327D, 327E, 328F, 328W, 328Y, and 332E. Exemplary substitutions include235Y, 236D, 239D, 266M, 267E, 268D, 268E, 328F, 328W, and 328Y. Other Fcvariants for enhancing binding to FcγRIIb include 235Y-267E, 236D-267E,239D-268D, 239D-267E, 267E-268D, 267E-268E, and 267E-328F. Specifically,the S267E, G236D, S239D, L328F and I332E variants, including theS267E-L328F double variant, of human IgG1 are of particular value inspecifically enhancing affinity for the inhibitory FcγRIIb receptor. Chuet al. (2008) Mol. Immunol. 45:3926; U.S. Pat. App. Pub. 2006/024298; WO2012/087928. Enhanced specificity for FcγRIIb (as distinguished fromFcγRIIa_(R131)) may be obtained by adding the P238D substitution andother mutations (Mimoto et al. (2013) Protein. Eng. Des. & Selection26:589; WO 2012/1152410), as well as V262E and V264E (Yu et al. (2013)J. Am. Chem. Soc. 135:9723, and WO 2014/184545.

Non-IgG2 Heavy Chain Constant Domains with IgG2 Hinge Regions

In some embodiments, anti-ICOS antibodies described herein exhibitincreased agonist activity at least in part due to modifications thatincreased binding to, and/or specificity for, FcγRIIb. An alternativeapproach is to engineer the Fc region to provide FcγR-independentenhancement of agonism. Examples of antibodies to other targets withmodified IgG2 domains providing such enhanced agonism are described atWO 2015/145360 and White et al. (2015) Cancer Cell 27:138, thedisclosures of which are hereby incorporated by reference in theirentireties. Specifically, disulfide bonds are arranged to “lock” theantibody into a more compact “h2B” conformation, resulting in enhancedagonism. The resulting enhanced agonism is FcγR-independent. (See Whiteet al. (2015) Cancer Cell 27:138). Such FcγR-independent agonism isadvantageous in treating some tumors, such as those that have fewFcγR-+expressing cells (e.g., few NK cells or macrophages). In oneembodiment, anti-ICOS antibodies comprising the CDR or variable domainsequences disclosed herein linked to non-hIgG2 heavy chain constantregions (e.g. IgG1) having hIgG2 hinge regions, or variants thereof,including CH1 domain sequence variants, are provided. In one embodiment,these “IgG2 hinge” antibodies exhibit enhanced agonism compared withantibodies with a fully IgG1 heavy chain constant region, and theenhanced agonism is independent of Fcγ receptor-mediated cross-linking.In some embodiments, these IgG2 hinge anti-ICOS antibodies retainsubstantially unchanged antigen binding affinity. Also provided hereinare methods of enhancing FcγR-independent agonism of non-IgG2 anti-ICOSantibodies comprising replacing the non-IgG2 hinge with an IgG2 hinge.In certain embodiments, a modified heavy chain constant region comprisesa hinge of the IgG2 isotype (an “IgG2 hinge”) and a CH1, CH2 and CH3domain, wherein at least one of the CH1, CH2 and CH3 domains is not ofthe IgG2 isotype. The IgG2 hinge may be a wildtype human IgG2 hinge(e.g., ERKCCVECPPCPAPPVAG, set forth in SEQ ID NO: 96) or a variantthereof that also confers enhanced agonist activity. In certainembodiments, such IgG2 hinge variants have similar rigidity or stiffnessas wildtype IgG2 hinge. The rigidity of a hinge can be determined, e.g.,by computer modeling, electron microscopy, spectroscopy such as NuclearMagnetic Resonance (NMR), X-ray crystallography (B-factors), orSedimentation Velocity Analytical ultracentrifugation to measure orcompare the radius of gyration of antibodies comprising the hinge. Insome embodiments, human IgG2 hinge variants comprise substitution(s) ofone or more of the four cysteine residues (i.e., C219, C220, C226 andC229), for example, with serine. In one embodiment, the IgG2 hingevariant comprises a C219S mutation (e.g., ERKSCVECPPCPAPPVAG, as setforth in SEQ ID NO: 110). Other IgG2 hinge variants comprise C220S,C226S or C229S mutation, any of which may be combined with a C219Smutation.

An IgG2 hinge variant may also comprise non-IgG2 hinge sequence elements(a “chimeric hinge”). In some embodiments, the rigidity of the chimerichinge is at least similar to that of a wildtype IgG2 hinge. For example,in one embodiment, an IgG2 hinge variant comprises a wildtype IgG1 lowerhinge. See Table 2.

Table 4 below provides examples of “IgG2 hinge” human heavy chainconstant region sequences differing in the isotypic origins of the CH1,CH2 and CH3 domains. As used herein, “IgG2 hinge antibody” refers notjust to antibodies comprising hinge regions derived from IgG2, but alsoCH1 regions derived from IgG2 CH1. The asterisk (*) in Table 4 indicatesthat the indicated domain may be of any isotype, or may be completelyabsent. In certain embodiments, a modified heavy chain constant regioncomprises a variant CH1 domain, e.g. including A114C and/or T173Cmutations. A modified heavy chain constant region may also comprise avariant CH2 domain, e.g. including A330S and/or P331S mutations.

TABLE 4 “IgG2 Hinge” Human Heavy Chain Constant Region Constructs CH1Hinge CH2 CH3 * IgG2 * * IgG1 IgG2 * * IgG2 IgG2 * * * IgG2 IgG1 * *IgG2 IgG2 * * IgG2 * IgG1 * IgG2 * IgG2 IgG1 IgG2 IgG1 * IgG1 IgG2IgG2 * IgG2 IgG2 IgG1 * IgG2 IgG2 IgG2 * IgG1 IgG2 * IgG1 IgG1 IgG2 *IgG2 IgG2 IgG2 * IgG1 IgG2 IgG2 * IgG2 * IgG2 IgG1 IgG1 * IgG2 IgG1IgG2 * IgG2 IgG2 IgG1 * IgG2 IgG2 IgG2 IgG1 IgG2 IgG1 IgG1 IgG1 IgG2IgG1 IgG2 IgG1 IgG2 IgG2 IgG1 IgG1 IgG2 IgG2 IgG2 IgG2 IgG2 IgG1 IgG1IgG2 IgG2 IgG1 IgG2 IgG2 IgG2 IgG2 IgG1 IgG2 IgG2 IgG2 IgG2

Examples of antibody constant domains comprising combinations of IgG2CH1 and hinge sequences with other isotype sequences, and select aminoacid substitutions, are provided by Table 5 below.

TABLE 5 Examples of “IgG2 Hinge” Human Heavy Chain Constant RegionsConstruct SEQ ID NO: Description IgG1f 104 wild type IgG1f IgG1.1f 109standard inert IgG1.1f IgG2.3 105 IgG2 A-form (C219S) IgG2.5 108 IgG2B-form (C131S) IgG2.3G1-KH 107 CH1, upper hinge and lower hinge/upperCH2 of IgG2.3, all else IgG1f IgG2.5G1-KH 116 CH1, upper hinge and lowerhinge/upper CH2 of IgG2.5, all else IgG1f IgG2.3G1-AY 106 CH1 and upperhinge of IgG2.3, all else IgG1f IgG2.5G1-AY 115 CH1 and upper hinge ofIgG2.5, all else IgG1f IgG1-G2.3G1-KH 119 CH1 of IgG1, upper hinge andlower hinge/upper CH2 of IgG2.3, all else IgG1f IgG1-G2.3G1-AY 118 CH1of IgG1, upper hinge of IgG2.3, all else IgG1f IgG2.3G1.1f-KH 110 CH1,upper hinge and lower hinge/upper CH2 of IgG2.3, all else IgG1.1fIgG2.5G1.1f-KH 114 CH1, upper hinge and lower hinge/upper CH2 of IgG2.5,all else IgG1.1f IgG1-deltaTHT 111 IgG1 with THT sequence removed fromhinge IgG2.3-plusTHT 112 IgG2.3 with THT sequence (from IgG1) added intohinge IgG2.5-plusTHT 117 IgG2.5 with THT sequence (from IgG1) added intohinge IgG2.3-plusGGG 113 IgG2.3 with flexible GGG sequence added intohinge

Additional specific examples of antibody constant domains comprisingcombinations of IgG2 CH1 and hinge sequences with other isotypesequences, and select amino acid substitutions, are provided by Table 6below.

TABLE 6 Additional Examples of “IgG2 Hinge” Human Heavy Chain ConstantRegions Construct SEQ ID NO: Description G2-G1-G1-G1 120 CH1 domain ofIgG2, with all else IgG1. Also, G2.5-G1-G1-G1 121 Cys > Ser mutant toreduce potential disulfide heterogeneity. G1-G2.3-G2-G2 122 CH1 domainof IgG1 with all else IgG2.3 G1-KRGEGSSNLF 123 Swap CH1 regions in IgG1with those of IgG2, G1-KRGEGS 124 either separately or together. G1-SNLF125 IgG1-ITNDRTPR 126 G1-SNLFPR 127 G2-RKEGSGNSFL 128 Swap CH1 regionsin IgG2 with those of IgG1, G2-RKEGSG 129 either separately or together.G2-NSFL 130 IgG2-TIDNTRRP 131 G2-NSFLRP 132 G1-G1-G2-G1-AY 133 IgG1 withCH2 domain residues of IgG2 G1-G1-G2-G1-KH 134 G2-G2.3-G1-G2-KH 135 IgG2with CH2 domain residues of IgG1 G2.5-G2.3-G1-G2-KH 136 G2-G2.3-G1-G2-AY137 G2.5-G2.3-G1-G2-AY 138 G1-G2.3-G1-G1-KH 139 Swap hinge regionsbetween IgG1 and IgG2. G2-G1-G2-G2-AY 140 G2.5-G1-G2-G2-AY 141G1-G2-G1-G1-AY 142 G2-G1-G2-G2-KH 143 G2.5-G1-G2-G2-KH 144IgG1-deltaHinge 145 Hinge truncations IgG2-deltaHinge 146IgG2.5-deltaHinge 147 IgG1-deltaG237 148 IgG2-plusG237 149 IgG2.4 150Other IgG2.3/4 151

Anti-ICOS antibodies, including antibodies comprising the CDR and/orvariable domain sequences disclosed herein, may incorporate the “IgG2hinge” constant domain sequences disclosed herein, e.g. to enhanceFcγR-independent agonist activity. Examples of such IgG2 hinge constantdomains include those disclosed by Table 5 (SEQ ID NOs: 104-108 and110-119) and Table 6 (SEQ ID NOs: 120-151), and also those disclosed atSEQ ID NOs: 101-108.

Half-Life Extension

In some embodiments, the anti-ICOS antibody is modified to increase itsbiological half-life, e.g., the antibody's half-life in serum. Variousapproaches are known in the art. For example, the half-life of anantibody may be extended by increasing the binding affinity of the Fcregion for FcRn. In one embodiment, the antibody is altered within theCH1 or CL region to contain a salvage receptor binding epitope takenfrom two loops of a CH2 domain of an Fc region of an IgG, as describedin U.S. Pat. Nos. 5,869,046 and 6,121,022 by Presta et al. Otherexemplary Fc variants that increase binding to FcRn and/or improvepharmacokinetic properties include substitutions at positions 259, 308,and 434, including for example 2591, 308F, 428L, 428M, 434S, 434H, 434F,434Y, and 434M. Other variants that increase Fc binding to FcRn include:250E, 250Q, 428L, 428F, 250Q/428L (Hinton et al., 2004, J. Biol. Chem.279(8): 6213-6216, Hinton et al. 2006 Journal of Immunology176:346-356), 256A, 272A, 305A, 307A, 311A, 312A, 378Q, 380A, 382A, 434A(Shields et al, Journal of Biological Chemistry, 2001,276(9):6591-6604), 252F, 252Y, 252W, 254T, 256Q, 256E, 256D, 433R, 434F,434Y, 252Y/254T/256E, 433K/434F/436H (Dall'Acqua et al. Journal ofImmunology, 2002, 169:5171-5180, Dall'Acqua et al., 2006, Journal ofBiological Chemistry 281:23514-23524). See U.S. Pat. No. 8,367,805.

Modification of certain conserved residues in IgG Fc (1253, H310, Q311,H433, N434), such as the N434A variant (Yeung et al. (2009) J. Immunol.182:7663), have been proposed as a way to increase FcRn affinity, thusincreasing the half-life of the antibody in circulation. (See, e.g., WO98/023289). The combination Fc variant comprising M428L and N434S hasbeen shown to increase FcRn binding and increase serum half-life up tofive-fold. (Zalevsky et al. (2010) Nat. Biotechnol. 28:157). Thecombination Fc variant comprising T307A, E380A and N434A modificationsalso extends half-life of IgG1 antibodies. (Petkova et al. (2006) Int.Immunol. 18:1759). In addition, combination Fc variants comprisingM252Y-M428L, M428L-N434H, M428L-N434F, M428L-N434Y, M428L-N434A,M428L-N434M, and M428L-N434S variants have also been shown to extendhalf-life. (WO 2009/086320).

Further, a combination Fc variant comprising M252Y, S254T and T256E,increases half-life-nearly four-fold. (Dall'Acqua et al. (2006) J. Biol.Chem. 281:23514). A related IgG1 modification providing increased FcRnaffinity but reduced pH dependence (M252Y-S254T-T256E-H433K-N434F) hasbeen used to create an IgG1 construct (“MST-HN Abdeg”) for use as acompetitor to prevent binding of other antibodies to FcRn, resulting inincreased clearance of that other antibody, either endogenous IgG (e.g.in an autoimmune setting) or another exogenous (therapeutic) mAb.(Vaccaro et al. (2005) Nat. Biotechnol. 23:1283; WO 2006/130834).

Other modifications for increasing FcRn binding are described in Yeunget al. (2010) J. Immunol. 182:7663-7671; 6,277,375; 6,821,505; WO97/34631; WO 2002/060919.

In certain embodiments, hybrid IgG isotypes may be used to increase FcRnbinding, and potentially increase half-life. For example, an IgG1/IgG3hybrid variant may be constructed by substituting IgG1 positions in theCH2 and/or CH3 region with the amino acids from IgG3 at positions wherethe two isotypes differ. Thus, a hybrid variant IgG antibody may beconstructed that comprises one or more substitutions, e.g., 274Q, 276K,300F, 339T, 356E, 358M, 384S, 392N, 397M, 4221, 435R, and 436F. In otherembodiments described herein, an IgG1/IgG2 hybrid variant may beconstructed by substituting IgG2 positions in the CH2 and/or CH3 regionwith amino acids from IgG1 at positions where the two isotypes differ.Thus, a hybrid variant IgG antibody may be constructed that comprisesone or more substitutions, e.g., one or more of the following amino acidsubstitutions: 233E, 234L, 235L, -236G (referring to an insertion of aglycine at position 236), and 327A. See U.S. Pat. No. 8,629,113. Ahybrid of IgG1/IgG2/IgG4 sequences has been generated that purportedlyincreases serum half-life and improves expression. U.S. Pat. No.7,867,491 (sequence number 18 therein).

The serum half-life of the antibodies described herein can also beincreased by pegylation. An antibody can be pegylated, for example, toincrease the biological (e.g., serum) half-life of the antibody. Topegylate an antibody, the antibody, or fragment thereof, typically isreacted with a polyethylene glycol (PEG) reagent, such as a reactiveester or aldehyde derivative of PEG, under conditions in which one ormore PEG groups become attached to the antibody or antibody fragment.Preferably, the pegylation is carried out via an acylation reaction oran alkylation reaction with a reactive PEG molecule (or an analogousreactive water-soluble polymer). As used herein, the term “polyethyleneglycol” is intended to encompass any of the forms of PEG that have beenused to derivatize other proteins, such as mono (C1-C10) alkoxy- oraryloxy-polyethylene glycol or polyethylene glycol-maleimide. In certainembodiments, the antibody to be pegylated is an aglycosylated antibody.Methods for pegylating proteins are known in the art and can be appliedto the antibodies described herein. (See, e.g., EP 0154316 by Nishimuraet al. and EP 0401384 by Ishikawa et al.

In some instances, it may be desirable to decrease the half-life of anantibody, rather than to increase it. In some embodiments, theantibodies described herein include modifications to decrease theirhalf-life. Modifications such as I253A (Hornick et al. (2000) J. Nucl.Med. 41:355) and H435A/R, I253A or H310A (Kim et al. (2000) Eur. J.Immunol. 29:2819) in Fc of human IgG1 can decrease FcRn binding, thusdecreasing half-life (increasing clearance) for use in situations whererapid clearance is preferred, such as for medical imaging. (See alsoKenanova et al. (2005) Cancer Res. 65:622). Other means to enhanceclearance include formatting the antigen binding domains of the presentinvention as antibody fragments lacking the ability to bind FcRn, suchas Fab fragments. Such modification can, for example, reduce thecirculating half-life of an antibody from a couple of weeks to hours.Selective PEGylation of antibody fragments can then be used to increasethe half-life of the antibody fragments when desired. (Chapman et al.(1999) Nat. Biotechnol. 17:780). Antibody fragments may also be fused tohuman serum albumin, e.g. in a fusion protein construct, to increasehalf-life. (Yeh et al. (1992) Proc. Nat'l Acad. Sci. 89:1904).Alternatively, a bispecific antibody may be constructed with a firstantigen binding domain of the present invention and a second antigenbinding domain that binds to human serum albumin (HSA). (See WO2009/127691 and patent references cited therein). Alternatively,specialized polypeptide sequences can be added to antibody fragments toincrease half-life, e.g. “XTEN” polypeptide sequences. (Schellenbergeret al. (2009) Nat. Biotechnol. 27:1186; Int'l Pat. Appl. Pub. WO2010/091122).

Additional Fc Variants

In some embodiments, when using an IgG4 constant domain, it can beadvantageous to include the substitution S228P, which mimics the hingesequence in IgG1 and thereby stabilizes IgG4 molecules, e.g. by reducingFab-arm exchange between the therapeutic antibody and endogenous IgG4 inthe patient being treated. (Labrijn et al. (2009) Nat. Biotechnol.27:767; Reddy et al. (2000) J. Immunol. 164:1925).

A potential protease cleavage site in the hinge of IgG1 constructs canbe eliminated by D221G and K222S modifications, increasing the stabilityof the antibody. (WO 2014/043344).

The affinities and binding properties of an Fc variant for its ligands(Fc receptors) may be determined by a variety of in vitro assay methods(e.g., biochemical or immunological based assays) known in the artincluding but not limited to, equilibrium methods (e.g., enzyme-linkedimmunosorbent assay (ELISA), or radioimmunoassay (RIA)), or kinetics(e.g., BIACORE® SPR analysis), and other methods such as indirectbinding assays, competitive inhibition assays, fluorescence resonanceenergy transfer (FRET), gel electrophoresis, and chromatography (e.g.,gel filtration). These and other methods may use a label on one or moreof the components being examined and/or employ various detection methodsincluding but not limited to chromogenic, fluorescent, luminescent, orisotopic labels. A detailed description of binding affinities andkinetics can be found in Paul, W. E., ed., Fundamental Immunology, 4thEd., Lippincott-Raven, Philadelphia (1999), which focuses onantibody-immunogen interactions.

In still other embodiments, the glycosylation of an antibody is modifiedto increase or decrease effector function. For example, an aglycoslatedantibody can be made that lacks all effector function by mutating theconserved asparagine residue at position 297 (e.g. N297A), thusabolishing complement and FcγRI binding. (Bolt et al. (1993) Eur. J.Immunol. 23:403. See also Tao & Morrison (1989) J. Immunol. 143:2595(using N297Q in IgG1 to eliminate glycosylation at position 297)).

Although aglycosylated antibodies generally lack effector function,mutations can be introduced to restore that function. Aglycosylatedantibodies, e.g. those resulting from N297A/C/D/or H mutations orproduced in systems (e.g. E. coli) that do not glycosylate proteins, canbe further mutated to restore FcγR binding, e.g. S298G and/or T299A/G/orH (WO 2009/079242), or E382V and M428I (Jung et al. (2010) Proc. Nat'lAcad. Sci. (USA) 107:604).

Glycoengineering can also be used to modify the anti-inflammatoryproperties of an IgG construct by changing the α2,6 sialyl content ofthe carbohydrate chains attached at Asn297 of the Fc regions, wherein anincreased proportion of α2,6 sialylated forms results in enhancedanti-inflammatory effects. (See Nimmerjahn et al. (2008) Ann. Rev.Immunol. 26:513). Conversely, reduction in the proportion of antibodieshaving α2,6 sialylated carbohydrates may be useful in cases whereanti-inflammatory properties are not wanted. Methods of modifying α2,6sialylation content of antibodies, for example, by selectivepurification of α2,6 sialylated forms or by enzymatic modification, areprovided at U.S. Pat. Appl. Pub. No. 2008/0206246. In other embodiments,the amino acid sequence of the Fc region may be modified to mimic theeffect of α2,6 sialylation, for example, by inclusion of an F241Amodification. (WO 2013/095966).

III. Antibody Physical Properties

In certain embodiments, the antibodies described herein contain one ormore glycosylation sites in either the light or heavy chain variableregion. Such glycosylation sites may result in increased immunogenicityof the antibody or an altered antibody pharmacokinetics due to alteredantigen binding (Marshall et al (1972) Ann. Rev. Biochem. 41:673-702;Gala and Morrison (2004) J. Immunol. 172:5489-94; Wallick et al (1988)J. Exp. Med. 168:1099-109; Spiro (2002) Glycobiology 12:43R-56R; Parekhet al (1985) Nature 316:452-7; Mimura et al. (2000) Mol Immunol37:697-706). Glycosylation has been known to occur at motifs containingan N-X-S/T sequence. In some embodiments, the anti-huICOS antibody doesnot contain variable region glycosylation. Such antibodies can beobtained by selecting antibodies that do not contain the glycosylationmotif in the variable region or by mutating residues within theglycosylation region.

In certain embodiments, the antibodies described herein do not containasparagine isomerism sites. The deamidation of asparagine may occur onN-G or D-G sequences and result in the creation of an isoaspartic acidresidue that introduces a kink into the polypeptide chain and decreasesits stability (known as the isoaspartic acid effect).

In some embodiments, the antibodies described herein have an isoelectricpoint (pI) in the pH range between 6 and 9.5. In some embodiments, theantibodies described herein have a pI in the pH range of 7-9.5 or 6-8.Antibodies having a pI within a desired pI range can be obtained eitherby selecting antibodies with a pI in the pH range from a group ofcandidates or by mutating charged surface residues of a particularantibody.

In some embodiments, the antibodies described herein are selected and/orengineered have a temperature of initial unfolding (T_(M1)) greater than60° C., greater than 65° C., or greater than 70° C. The melting point ofan antibody may be measured using differential scanning calorimetry(Chen et al (2003) Pharm Res 20:1952-60; Ghirlando et al (1999) ImmunolLett. 68:47-52) or circular dichroism (Murray et al. (2002) J.Chromatogr. Sci. 40:343-9).

In some embodiments, the antibodies described herein are selected and/orengineered to have advantageous degradation properties, e.g., slowdegradation in vitro and/or in vivo. Antibody degradation can bemeasured using capillary electrophoresis (CE) and MALDI-MS (Alexander AJ and Hughes D E (1995) Anal Chem. 67:3626-32). In some embodiments, theantibodies described herein are selected and/or engineered to havefavorable aggregation properties, e.g., antibodies that show minimalaggregation in vitro and/or in vivo, which may elicit an unwanted immuneresponse and/or altered or unfavorable pharmacokinetic properties. Insome embodiments, the antibodies described herein show aggregation of25% or less, 20% or less, 15% or less, 10% or less, or 5% or lesscompared to aggregation of the parent antibody. Aggregation can bemeasured by several techniques, including size-exclusion column (SEC),high performance liquid chromatography (HPLC), and light scattering.

IV. Nucleic Acid Molecules and Recombinant Methods

Another aspect described herein pertains to nucleic acid molecules thatencode the anti-huICOS antibodies described herein. The nucleic acidsmay be present in whole cells e.g., a host cell, in a cell lysate, or ina partially purified or substantially pure form. A nucleic acid is“isolated” or “rendered substantially pure” when purified away fromother cellular components or other contaminants, e.g., other cellularnucleic acids (e.g., other chromosomal DNA, e.g., the chromosomal DNAthat is linked to the isolated DNA in nature) or proteins, by standardtechniques, including alkaline/SDS treatment, CsCl banding, columnchromatography, restriction enzymes, agarose gel electrophoresis, andothers well known in the art. (See, F. Ausubel, et al., ed. (1987)Current Protocols in Molecular Biology, Greene Publishing and WileyInterscience, New York). A nucleic acid described herein can be, forexample, DNA or RNA and may or may not contain introns. In a certainembodiments, the nucleic acid is a cDNA molecule.

Nucleic acids described herein can be obtained using standard molecularbiology techniques. For antibodies expressed by hybridomas (e.g.,hybridomas prepared from transgenic mice carrying human immunoglobulingenes as described further below), cDNAs encoding the light and/or heavychains of the antibody made by the hybridoma can be obtained by standardPCR amplification or cDNA cloning techniques. For antibodies obtainedfrom an immunoglobulin gene library (e.g., using phage displaytechniques), nucleic acid encoding the antibody can be recovered fromthe library.

Once DNA fragments encoding V_(H) and V_(L) segments are obtained, theseDNA fragments can be further manipulated by standard recombinant DNAtechniques, for example, to convert the variable region genes tofull-length antibody chain genes, to Fab fragment genes or to a scFvgene. In these manipulations, a V_(L)- or V_(H)-encoding DNA fragment isoperatively linked to another DNA fragment encoding another protein,such as an antibody constant region or a flexible linker. The term“operatively linked,” as used in this context, means that the two DNAfragments are joined such that the amino acid sequences encoded by thetwo DNA fragments remain in-frame.

Isolated DNA encoding the V_(H) region can be converted to a full-lengthheavy chain gene by operatively linking the V_(H)-encoding DNA toanother DNA molecule encoding heavy chain constant regions (hinge, CH1,CH2 and/or CH3). The sequences of human heavy chain constant regiongenes are known in the art (see e.g., Kabat, et al., 1991), and DNAfragments encompassing these regions can be obtained by standard PCRamplification. The heavy chain constant region can be an IgG (IgG1,IgG2, IgG3, or IgG4), IgA, IgE, IgM or IgD constant region, for example,an IgG1 region. For a Fab fragment heavy chain gene, the V_(H)-encodingDNA can be operatively linked to another DNA molecule encoding only theheavy chain CH1 constant region.

The isolated DNA encoding the V_(L) region can be converted to afull-length light chain gene (as well as a Fab light chain gene) byoperatively linking the V_(L)-encoding DNA to another DNA moleculeencoding the light chain constant region, CL. The sequences of humanlight chain constant region genes are known in the art (see e.g., Kabat,et al., 1991) Sequences of Proteins of Immunological Interest, FifthEdition, U.S. Department of Health and Human Services, NIH PublicationNo. 91-3242), and DNA fragments encompassing these regions can beobtained by standard PCR amplification. The light chain constant regioncan be a kappa or lambda constant region.

To create a scFv gene, the V_(H)- and V_(L)-encoding DNA fragments areoperatively linked to another fragment encoding a flexible linker, e.g.,encoding the amino acid sequence (Gly₄-Ser)₃, such that the V_(H) andV_(L) sequences can be expressed as a contiguous single-chain protein,with the V_(L) and V_(H) regions joined by the flexible linker (seee.g., Bird et al. (1988) Science 242:423-426; Huston et al. (1988) Proc.Natl. Acad. Sci. USA 85:5879-5883; McCafferty et al., (1990) Nature348:552-554).

V. Antibody Generation

Various antibodies of the present invention, e.g. those that bind to thesame epitope as selected anti-human ICOS antibodies disclosed herein,can be produced using a variety of known techniques, such as thestandard somatic cell hybridization technique described by Kohler andMilstein, Nature 256: 495 (1975). Other techniques for producingmonoclonal antibodies also can be employed, e.g., viral or oncogenictransformation of B lymphocytes, phage display technique using librariesof human antibody genes.

An exemplary animal system for preparing hybridomas is the murinesystem. Hybridoma production in the mouse is a well-establishedprocedure. Immunization protocols and techniques for isolation ofimmunized splenocytes for fusion are known in the art. Fusion partners(e.g., murine myeloma cells) and fusion procedures are also known.

Chimeric or humanized antibodies described herein can be prepared basedon the sequence of a murine monoclonal antibody prepared as describedabove. DNA encoding the heavy and light chain immunoglobulins can beobtained from the murine hybridoma of interest and engineered to containnon-murine (e.g., human) immunoglobulin sequences using standardmolecular biology techniques. For example, to create a chimericantibody, the murine variable regions can be linked to human constantregions using methods known in the art (see e.g., U.S. Pat. No.4,816,567 to Cabilly et al.). To create a humanized antibody, the murineCDR regions can be inserted into a human framework using methods knownin the art (see e.g., U.S. Pat. No. 5,225,539 to Winter, and U.S. Pat.Nos. 5,530,101; 5,585,089; 5,693,762 and 6,180,370 to Queen et al.).

In one embodiment, the antibodies described herein are human monoclonalantibodies. Such human monoclonal antibodies directed against human ICOScan be generated using transgenic or transchromosomic mice carryingparts of the human immune system rather than the mouse system. Thesetransgenic and transchromosomic mice include mice referred to herein asHuMAb mice and KM mice, respectively, and are collectively referred toherein as “human Ig mice.”

The HuMAb Mouse® (Medarex, Inc.) contains human immunoglobulin geneminiloci that encode un-rearranged human heavy (μ and γ) and κ lightchain immunoglobulin sequences, together with targeted mutations thatinactivate the endogenous μ and κ chain loci (see e.g., Lonberg, et al.(1994) Nature 368(6474): 856-859). Accordingly, the mice exhibit reducedexpression of mouse IgM or κ, and in response to immunization, theintroduced human heavy and light chain transgenes undergo classswitching and somatic mutation to generate high affinity human IgGκmonoclonal antibodies (Lonberg, N. et al. (1994), supra; reviewed inLonberg, N. (1994) Handbook of Experimental Pharmacology 113:49-101;Lonberg, N. and Huszar, D. (1995) Intern. Rev. Immunol. 13: 65-93, andHarding, F. and Lonberg, N. (1995) Ann. N.Y. Acad. Sci. 764:536-546).The preparation and use of HuMab mice, and the genomic modificationscarried by such mice, is further described in Taylor, L. et al. (1992)Nucleic Acids Research 20:6287-6295; Chen, J. et al. (1993)International Immunology 5: 647-656; Tuaillon et al. (1993) Proc. Natl.Acad. Sci. USA 90:3720-3724; Choi et al. (1993) Nature Genetics4:117-123; Chen, J. et al. (1993) EMBO J. 12: 821-830; Tuaillon et al.(1994) J. Immunol. 152:2912-2920; Taylor, L. et al. (1994) InternationalImmunology 6: 579-591; and Fishwild, D. et al. (1996) NatureBiotechnology 14: 845-851, the contents of all of which are herebyspecifically incorporated by reference in their entirety. (See, also,U.S. Pat. Nos. 5,545,806; 5,569,825; 5,625,126; 5,633,425; 5,789,650;5,877,397; 5,661,016; 5,814,318; 5,874,299; and 5,770,429; all toLonberg and Kay; U.S. Pat. No. 5,545,807 to Surani et al.; PCTPublication Nos. WO 92/03918, WO 93/12227, WO 94/25585, WO 97/13852, WO98/24884 and WO 99/45962, all to Lonberg and Kay; and PCT PublicationNo. WO 01/14424 to Korman et al.)

In certain embodiments, antibodies described herein are raised using amouse that carries human immunoglobulin sequences on transgenes andtranschromosomes, such as a mouse that carries a human heavy chaintransgene and a human light chain transchromosome. Such mice, referredto herein as “KM mice”, are described in detail in PCT Publication WO02/43478 to Ishida et al.

Still further, alternative transgenic animal systems expressing humanimmunoglobulin genes are available in the art and can be used to raiseanti-huICOS antibodies described herein. For example, an alternativetransgenic system referred to as the Xenomouse (Abgenix, Inc.) can beused; such mice are described in, for example, U.S. Pat. Nos. 5,939,598;6,075,181; 6,114,598; 6, 150,584 and 6,162,963 to Kucherlapati et al.

Moreover, alternative transchromosomic animal systems expressing humanimmunoglobulin genes are available in the art and can be used to raiseanti-ICOS antibodies described herein. For example, mice carrying both ahuman heavy chain transchromosome and a human light chaintranschromosome, referred to as “TC mice” can be used; such mice aredescribed in Tomizuka et al. (2000) Proc. Natl. Acad. Sci. USA97:722-727. Furthermore, cows carrying human heavy and light chaintranschromosomes have been described in the art (Kuroiwa et al. (2002)Nature Biotechnology 20:889-894) and can be used to raise anti-huICOSantibodies described herein.

Additional mouse systems described in the art for raising humanantibodies, e.g., human anti-huICOS antibodies, include (i) theVELOCIMMUNE® mouse (Regeneron Pharmaceuticals, Inc.), in which theendogenous mouse heavy and light chain variable regions have beenreplaced, via homologous recombination, with human heavy and light chainvariable regions, operatively linked to the endogenous mouse constantregions, such that chimeric antibodies (human V/mouse C) are raised inthe mice, and then subsequently converted to fully human antibodiesusing standard recombinant DNA techniques; and (ii) the MeMo® mouse(Merus Biopharmaceuticals, Inc.), in which the mouse containsun-rearranged human heavy chain variable regions but a single rearrangedhuman common light chain variable region. Such mice, and use thereof toraise antibodies, are described in, for example, WO 2009/15777, US2010/0069614, WO 2011/072204, WO 2011/097603, WO 2011/163311, WO2011/163314, WO 2012/148873, US 2012/0070861 and US 2012/0073004.

Human monoclonal antibodies described herein can also be prepared usingphage display methods for screening libraries of human immunoglobulingenes. Such phage display methods for isolating human antibodies areestablished in the art. (See, e.g., U.S. Pat. Nos. 5,223,409; 5,403,484;and 5,571,698 to Ladner et al.; U.S. Pat. Nos. 5,427,908 and 5,580,717to Dower et al.; U.S. Pat. Nos. 5,969,108 and 6,172,197 to McCafferty etal.; and U.S. Pat. Nos. 5,885,793; 6,521,404; 6,544,731; 6,555,313;6,582,915 and 6,593,081 to Griffiths et al.).

Human monoclonal antibodies described herein can also be prepared usingmice with severe combined immunodeficiency (SCID) into which humanimmune cells have been reconstituted such that a human antibody responsecan be generated upon immunization. Such mice are described in, forexample, U.S. Pat. Nos. 5,476,996 and 5,698,767 to Wilson et al.

Immunizations

To generate fully human antibodies to human ICOS, mice or transgenic ortranschromosomal mice containing human immunoglobulin genes (e.g.,HCo12, HCo7 or KM mice) can be immunized with a purified or enrichedpreparation of the ICOS antigen and/or cells expressing ICOS, asdescribed for other antigens, for example, by Lonberg et al. (1994)Nature 368(6474): 856-859; Fishwild et al. (1996) Nature Biotechnology14: 845-851 and WO 98/24884. Alternatively, mice can be immunized withDNA encoding human ICOS. Preferably, the mice will be 6-16 weeks of ageupon the first infusion. For example, a purified or enriched preparation(e.g, 5 μg-50 μg) of the recombinant human ICOS antigen can be used toimmunize the mice intraperitoneally. If the immunizations using apurified or enriched preparation of the ICOS antigen do not result inantibodies, mice can also be immunized with cells expressing ICOS, e.g.,a cell line, to promote immune responses.

The HuMAb transgenic mice can be initially immunized intraperitoneallyor subcutaneously (SC) with antigen in Ribi's adjuvant, followed byevery other week IP/SC immunizations (up to a total of 10) with antigenin Ribi's adjuvant. The immune response can be monitored over the courseof the immunization protocol with plasma samples being obtained byretroorbital bleeds. The plasma can be screened by ELISA and FACS (asdescribed below), and mice with sufficient titers of anti-ICOS humanimmunoglobulin can be used for fusions. Mice can be boostedintravenously with antigen three days before sacrifice and removal ofthe spleen and lymph nodes. Two to three fusions for each immunizationmay be performed. Between 6 and 24 mice can be immunized for eachantigen. In some embodiments, HCo7, HCo12, and KM strains are used. Inaddition, both HCo7 and HCo12 transgene can be bred together into asingle mouse having two different human heavy chain transgenes(HCo7/HCo12).

Generation of Hybridomas Producing Monoclonal Antibodies to ICOS

To generate hybridomas producing monoclonal antibodies described herein,splenocytes and/or lymph node cells from immunized mice can be isolatedand fused to an appropriate immortalized cell line, such as a mousemyeloma cell line. The resulting hybridomas can be screened for theproduction of antigen-specific antibodies. For example, single cellsuspensions of splenic lymphocytes from immunized mice can be fused toSp2/0 non-secreting mouse myeloma cells (ATCC, CRL 1581) with 50% PEG.Cells are plated at approximately 2×10⁵ in flat bottom microtiter plate,followed by a two week incubation in selective medium containing 10%fetal Clone Serum, 18% “653” conditioned media, 5% Origen (IGEN), 4 mML-glutamine, 1 mM sodium pyruvate, 5 mM HEPES, 0.055 mM2-mercaptoethanol, 50 units/ml penicillin, 50 mg/ml streptomycin, 50mg/ml gentamycin and 1×HAT (Sigma). After approximately two weeks, cellscan be cultured in medium in which the HAT is replaced with HT.Individual wells can then be screened by ELISA for human monoclonal IgMand IgG antibodies. Once extensive hybridoma growth occurs, medium canbe observed usually after 10-14 days. The antibody secreting hybridomascan be re-plated, screened again, and, if still positive for human IgG,the monoclonal antibodies can be subcloned at least twice by limitingdilution. The stable subclones can then be cultured in vitro to generatesmall amounts of antibody in tissue culture medium for characterization.

To purify monoclonal antibodies, selected hybridomas can be grown intwo-liter spinner-flasks for monoclonal antibody purification.Supernatants can be filtered and concentrated before affinitychromatography with protein A-sepharose (Pharmacia, Piscataway, N.J.).Eluted IgG can be checked by gel electrophoresis and high performanceliquid chromatography to ensure purity. The buffer solution can beexchanged into PBS, and the concentration can be determined by OD280using 1.43 extinction coefficient. The monoclonal antibodies can bealiquoted and stored at −80° C.

VI. Antibody Manufacture

Generation of Transfectomas Producing Monoclonal Antibodies to ICOS

Antibodies of the present invention, including both specific antibodiesfor which sequences are provided and other, related anti-ICOSantibodies, can be produced in a host cell transfectoma using, forexample, a combination of recombinant DNA techniques and genetransfection methods well known in the art (Morrison, S. (1985) Science229:1202).

For example, to express antibodies, or antibody fragments thereof, DNAsencoding partial or full-length light and heavy chains, can be obtainedby standard molecular biology techniques (e.g., PCR amplification orcDNA cloning using a hybridoma that expresses the antibody of interest),and the DNAs can be inserted into expression vectors such that the genesare operatively linked to transcriptional and translational controlsequences. In this context, the term “operatively linked” is intended tomean that an antibody gene is ligated into a vector such thattranscriptional and translational control sequences within the vectorserve their intended function of regulating the transcription andtranslation of the antibody gene. The expression vector and expressioncontrol sequences are chosen to be compatible with the expression hostcell used. The antibody light chain gene and the antibody heavy chaingene can be inserted into separate vector or both genes are insertedinto the same expression vector. The antibody genes are inserted intothe expression vector(s) by standard methods (e.g., ligation ofcomplementary restriction sites on the antibody gene fragment andvector, or blunt end ligation if no restriction sites are present). Thelight and heavy chain variable regions of the antibodies describedherein can be used to create full-length antibody genes of any antibodyisotype by inserting them into expression vectors already encoding heavychain constant and light chain constant regions of the desired isotypesuch that the V_(H) segment is operatively linked to the C_(H)segment(s) within the vector and the V_(L) segment is operatively linkedto the C_(L) segment within the vector. Additionally or alternatively,the recombinant expression vector can encode a signal peptide thatfacilitates secretion of the antibody chain from a host cell. Theantibody chain gene can be cloned into the vector such that the signalpeptide is linked in-frame to the amino terminus of the antibody chaingene. The signal peptide can be an immunoglobulin signal peptide or aheterologous signal peptide (i.e., a signal peptide from anon-immunoglobulin protein).

In addition to the antibody chain genes, recombinant expression vectorsmay carry regulatory sequences that control the expression of theantibody chain genes in a host cell. The term “regulatory sequence”includes promoters, enhancers, and other expression control elements(e.g., polyadenylation signals) that control the transcription ortranslation of the antibody chain genes. Such regulatory sequences aredescribed, for example, in Goeddel (Gene Expression Technology. Methodsin Enzymology 185, Academic Press, San Diego, Calif. (1990)). It will beappreciated by those skilled in the art that the design of theexpression vector, including the selection of regulatory sequences, maydepend on such factors as the choice of the host cell to be transformed,the level of expression of protein desired, amongst other factors.Preferred regulatory sequences for mammalian host cell expressioninclude viral elements that direct high levels of protein expression inmammalian cells, such as promoters and/or enhancers derived fromcytomegalovirus (CMV), Simian Virus 40 (SV40), adenovirus, (e.g., theadenovirus major late promoter (AdMLP), and polyomavirus. Alternatively,nonviral regulatory sequences may be used, such as the ubiquitinpromoter or β-globin promoter. Still further, regulatory elementscomposed of sequences from different sources, such as the SRα promotersystem, which contains sequences from the SV40 early promoter and thelong terminal repeat of human T cell leukemia virus type 1 (Takebe, Y.et al. (1988) Mol. Cell. Biol. 8:466-472).

In addition to the antibody chain genes and regulatory sequences,recombinant expression vectors may carry additional sequences, such assequences that regulate replication of the vector in host cells (e.g.,origins of replication) and selectable marker genes. The selectablemarker gene facilitates selection of host cells into which the vectorhas been introduced (see, e.g., U.S. Pat. Nos. 4,399,216, 4,634,665 and5,179,017, all by Axel et al.). For example, typically the selectablemarker gene confers resistance to drugs, such as G418, hygromycin ormethotrexate, on a host cell into which the vector has been introduced.Exemplary selectable marker genes include the dihydrofolate reductase(DHFR) gene (for use in dhfr-host cells with methotrexateselection/amplification) and the neo gene (for G418 selection).

For expression of the light and heavy chains, the expression vector(s)encoding the heavy and light chains is transfected into a host cell bystandard techniques. The various forms of the term “transfection”encompasses a wide variety of techniques commonly used for theintroduction of exogenous DNA into a prokaryotic or eukaryotic hostcell, e.g., electroporation, calcium-phosphate precipitation,DEAE-dextran transfection and the like. Although it is theoreticallypossible to express the antibodies described herein in eitherprokaryotic or eukaryotic host cells, expression of antibodies ineukaryotic cells, and most preferably mammalian host cells, is the mostpreferred because such eukaryotic cells, and in particular mammaliancells, are more likely than prokaryotic cells to assemble and secrete aproperly folded and immunologically active antibody. Prokaryoticexpression of antibody genes has been reported to be ineffective forproduction of high yields of active antibody (Boss, M. A. and Wood, C.R. (1985) Immunology Today 6:12-13). Antibodies of the present inventioncan also be produced in glycol-engineered strains of yeast. (Pichiapastoris. Li et al. (2006) Nat. Biotechnol. 24:210).

Exemplary mammalian host cells for expressing the recombinant antibodiesdescribed herein include Chinese Hamster Ovary (CHO cells) (includingdhfr-CHO cells, described in Urlaub and Chasin, (1980) Proc. Natl. Acad.Sci. USA 77:4216-4220, used with a dihydrofolate reductase (DHFR)selectable marker, e.g., as described in R. J. Kaufman and P. A. Sharp(1982) Mol. Biol. 159:601-621), NSO myeloma cells, COS cells and SP2cells. In particular, for use with NSO myeloma cells, another exemplaryexpression system is the GS gene expression system disclosed in WO87/04462, WO 89/01036 and EP 338,841. When recombinant expressionvectors encoding antibody genes are introduced into mammalian hostcells, the antibodies are produced by culturing the host cells for aperiod of time sufficient to allow for expression of the antibody in thehost cells or, more preferably, secretion of the antibody into theculture medium in which the host cells are grown. Antibodies can berecovered from the culture medium using standard protein purificationmethods.

The N- and C-termini of antibody polypeptide chains of the presentinvention may differ from the expected sequence due to commonly observedpost-translational modifications. For example, C-terminal lysineresidues are often missing from antibody heavy chains. (Dick et al.(2008) Biotechnol. Bioeng. 100:1132). N-terminal glutamine residues, andto a lesser extent glutamate residues, are frequently converted topyroglutamate residues on both light and heavy chains of therapeuticantibodies. (Dick et al. (2007) Biotechnol. Bioeng. 97:544; Liu et al.(2011) JBC 28611211; Liu et al. (2011) J. Biol. Chem. 286:11211).

Amino acid sequences for various agonist anti-huICOS antibodies of thepresent invention are provided in the Sequence Listing, which issummarized at Table 35. For the reasons discussed above, the C-terminallysine is not included in many of sequences in the Sequence Listing forheavy chains or heavy chain constant domains. However, in an alternativeembodiment, each heavy chain for the anti-huICOS antibodies of thepresent invention, and/or genetic construct encoding such antibodies orthe heavy or light chains thereof, includes this additional lysineresidue at the C-terminus of the heavy chain(s).

VII. Assays

Antibodies described herein can be tested for binding to ICOS by, forexample, standard ELISA. For example, microtiter plates are coated withpurified ICOS at 1-2 μg/ml in PBS, and then blocked with 5% bovine serumalbumin in PBS. Dilutions of antibody (e.g., dilutions of plasma fromICOS-immunized mice) are added to each well and incubated for 1-2 hoursat 37° C. The plates are washed with PBS/Tween and then incubated withsecondary reagent (e.g., for human antibodies, or antibodies otherwisehaving a human heavy chain constant region, a goat-anti-human IgGFc-specific polyclonal reagent) conjugated to horseradish peroxidase(HRP) for 1 hour at 37° C. After washing, the plates are developed withABTS substrate (Moss Inc, product: ABTS-1000) and analyzed by aspectrophotometer at OD 415-495. Sera from immunized mice are thenfurther screened by flow cytometry for binding to a cell line expressinghuman ICOS, but not to a control cell line that does not express ICOS.Briefly, the binding of anti-ICOS antibodies is assessed by incubatingICOS expressing CHO cells with the anti-ICOS antibody at 1:20 dilution.The cells are washed and binding is detected with a PE-labeledanti-human IgG Ab. Flow cytometric analyses are performed using aFACScan flow cytometry (Becton Dickinson, San Jose, Calif.). Preferably,mice that develop the highest titers will be used for fusions. Analogousexperiments may be performed using anti-mouse detection antibodies ifmouse anti-huICOS antibodies are to be detected.

An ELISA, e.g., as described above can be used to screen for antibodiesand, thus, hybridomas that produce antibodies that show positivereactivity with the ICOS immunogen. Hybridomas that produce antibodiesthat bind, preferably with high affinity, to ICOS can then be subclonedand further characterized. One clone from each hybridoma, which retainsthe reactivity of the parent cells (by ELISA), can then be chosen formaking a cell bank, and for antibody purification.

To purify anti-ICOS antibodies, selected hybridomas can be grown intwo-liter spinner-flasks for monoclonal antibody purification.Supernatants can be filtered and concentrated before affinitychromatography with protein A-sepharose (Pharmacia, Piscataway, N.J.).Eluted IgG can be checked by gel electrophoresis and high performanceliquid chromatography to ensure purity. The buffer solution can beexchanged into PBS, and the concentration can be determined by OD₂₈₀using 1.43 extinction coefficient. The monoclonal antibodies can bealiquoted and stored at −80° C.

To determine if the selected anti-ICOS monoclonal antibodies bind tounique epitopes, each antibody can be biotinylated using commerciallyavailable reagents (Pierce, Rockford, Ill.). Biotinylated MAb bindingcan be detected with a streptavidin labeled probe. Competition studiesusing unlabeled monoclonal antibodies and biotinylated monoclonalantibodies can be performed using ICOS coated-ELISA plates as describedabove.

To determine the isotype of purified antibodies, isotype ELISAs can beperformed using reagents specific for antibodies of a particularisotype. For example, to determine the isotype of a human monoclonalantibody, wells of microtiter plates can be coated with 1 μg/ml ofanti-human immunoglobulin overnight at 4° C. After blocking with 1% BSA,the plates are reacted with 1 μg/ml or less of test monoclonalantibodies or purified isotype controls, at ambient temperature for oneto two hours. The wells can then be reacted with either human IgG1 orhuman IgM-specific alkaline phosphatase-conjugated probes. Plates aredeveloped and analyzed as described above.

To test the binding of monoclonal antibodies to live cells expressingICOS, flow cytometry can be used. Briefly, cell lines expressingmembrane-bound ICOS (grown under standard growth conditions) are mixedwith various concentrations of monoclonal antibodies in PBS containing0.1% BSA at 4° C. for one hour. After washing, the cells are reactedwith Phycoerythrin (PE)-labeled anti-IgG antibody under the sameconditions as the primary antibody staining. The samples can be analyzedby FACScan instrument using light and side scatter properties to gate onsingle cells and binding of the labeled antibodies is determined. Analternative assay using fluorescence microscopy may be used (in additionto or instead of) the flow cytometry assay. Cells can be stained exactlyas described above and examined by fluorescence microscopy. This methodallows visualization of individual cells, but may have diminishedsensitivity depending on the density of the antigen.

Anti-huICOS antibodies can be further tested for reactivity with theICOS antigen by Western blotting. Briefly, cell extracts from cellsexpressing ICOS can be prepared and subjected to sodium dodecyl sulfatepolyacrylamide gel electrophoresis. After electrophoresis, the separatedantigens will be transferred to nitrocellulose membranes, blocked with20% mouse serum, and probed with the monoclonal antibodies to be tested.IgG binding can be detected using anti-IgG alkaline phosphatase anddeveloped with BCIP/NBT substrate tablets (Sigma Chem. Co., St. Louis,Mo.).

Methods for analyzing binding affinity, cross-reactivity, and bindingkinetics of various anti-ICOS antibodies include standard assays knownin the art, for example, Biolayer Interferometry (BLI) analysis, andBIACORE® SPR analysis using a BIACORE® 2000 SPR instrument (Biacore AB,Uppsala, Sweden).

In one embodiment, an anti-huICOS antibody specifically binds to theextracellular region of human ICOS. In one embodiment, the antibodybinds to a particular domain (e.g., a functional domain) within theextracellular domain of ICOS. In one embodiment, the anti-huICOSantibody specifically binds to the extracellular region of human ICOSand the extracellular region of cynomolgus ICOS. In one embodiment, theanit-huICOS antibody binds to human ICOS with high affinity.

VIII. Multispecific Molecules

In certain embodiments, antibodies described herein may bemultispecific, e.g., bispecific or trispecific, molecules. Multispecificantigen-binding molecules, such as multispecific antibodies, comprisetwo or more antigen-binding site, each specific for a different epitope.The different epitope can be part of the same or different antigens. Inone embodiment, one antigen-binding site is specific for human ICOS andthe other for a different antigen. In one embodiment, an anti-huICOSantibody, or antigen-binding fragments thereof, as described herein islinked to another antigen-binding molecule, e.g., another peptide orprotein (e.g., another antibody or antibody fragment, or a ligand for areceptor) having a different binding specificity to generate abispecific molecule that binds to at least two different binding sitesor target molecules. In one embodiment, the antibody described herein isderivatized or linked to more than one other antigen-binding molecule togenerate multispecific molecules that bind to more than two differentbinding sites and/or target molecules. Accordingly, provided herein arebispecific molecules comprising at least one first binding specificityfor ICOS and a second binding specificity for a second target epitope.In an embodiment described herein in which the bispecific molecule ismultispecific, the molecule can further include a third bindingspecificity.

In one embodiment, the bispecific molecules described herein comprise asa binding specificity at least one antibody, or an antibody fragmentthereof, including, e.g., an Fab, Fab′, F(ab′)₂, Fv, or a single chainFv. The antibody may also be a light chain or heavy chain dimer, or anyminimal fragment thereof such as a Fv or a single chain construct asdescribed in Ladner et al. U.S. Pat. No. 4,946,778, the contents ofwhich is expressly incorporated by reference.

While human monoclonal antibodies are preferred, other antibodies thatcan be employed in the bispecific molecules described herein are murine,chimeric and humanized monoclonal antibodies.

The bispecific molecules described herein can be prepared by conjugatingthe constituent binding specificities using methods known in the art.For example, each binding specificity of the bispecific molecule can begenerated separately and then conjugated to one another. When thebinding specificities are proteins or peptides, a variety of coupling orcross-linking agents can be used for covalent conjugation. Examples ofcross-linking agents include protein A, carbodiimide,N-succinimidyl-S-acetyl-thioacetate (SATA),5,5′-dithiobis(2-nitrobenzoic acid) (DTNB), o-phenylenedimaleimide(oPDM), N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP), andsulfosuccinimidyl 4-(N-maleimidomethyl) cyclohaxane-1-carboxylate(sulfo-SMCC) (see e.g., Karpovsky et al. (1984) J. Exp. Med. 160:1686;Liu, M A et al. (1985) Proc. Natl. Acad. Sci. USA 82:8648). Othermethods include those described in Paulus (1985) Behring Ins. Mitt. No.78, 118-132; Brennan et al. (1985) Science 229:81-83), and Glennie etal. (1987) J. Immunol. 139: 2367-2375). Preferred conjugating agents areSATA and sulfo-SMCC, both available from Pierce Chemical Co. (Rockford,Ill.).

When the binding specificities are antibodies, they can be conjugatedvia sulfhydryl bonding of the C-terminus hinge regions of the two heavychains. In a particularly preferred embodiment, the hinge region ismodified to contain an odd number of sulfhydryl residues, preferablyone, prior to conjugation.

Alternatively, both binding specificities can be encoded in the samevector and expressed and assembled in the same host cell. This method isparticularly useful where the bispecific molecule has a combination ofbinding specificities such as a (mAb×mAb), (mAb×Fab), (Fab×F(ab′)₂) or(ligand x Fab) fusion protein. A bispecific molecule described hereincan be a single chain molecule comprising one single chain antibody anda binding determinant, or a single chain bispecific molecule comprisingtwo binding determinants. Bispecific molecules may comprise at least twosingle chain molecules. Methods for preparing bispecific molecules aredescribed for example in U.S. Pat. Nos. 5,260,203; 5,455,030; 4,881,175;5,132,405; 5,091,513; 5,476,786; 5,013,653; 5,258,498; and 5,482,858.

Binding of the bispecific molecules to their specific targets can beconfirmed using art-recognized methods, such as using ELISA,radioimmunoassay (RIA), FACS analysis, bioassay (e.g., growthinhibition), or Western Blot assay. Each of these assays generallydetects the presence of protein-antibody complexes of particularinterest by employing a labeled reagent (e.g., an antibody) specific forthe complex of interest.

IX. Compositions

Further provided are compositions, e.g., a pharmaceutical compositions,containing one or more anti-ICOS antibodies, or antigen-bindingfragment(s) thereof, as described herein, formulated together with apharmaceutically acceptable carrier. Accordingly, the compositions ofthe present invention include the human or humanized anti-huICOSantibodies (or antigen-binding fragments) thereof having the CDRsequences, the heavy and/or light chain variable region sequences, orthe full-length heavy and/or light chain sequences set forth in Table35. Compositions of the present invention also include anti-huICOSantibodies having sequences which are variants of the sequences setforth in Table 35. For example, such antibodies can comprise sequencesthat are at least 70%, 75%, 80%, 85%, 90%, or 95%, 96%, 97%, 98%, or 99%identical to the CDR sequences, the heavy and/or light chain variableregion sequences, or full-length heavy and/or light chain sequences setforth in Table 35.

Such compositions also may include one or a combination of (e.g., two ormore different) antibodies, or immunoconjugates or bispecific moleculesdescribed herein. For example, a pharmaceutical composition describedherein can comprise a combination of antibodies (or immunoconjugates orbispecific antibodies) that bind to different epitopes on the targetantigen or that have complementary activities.

Pharmaceutical compositions described herein also can be administered ascombination therapy, i.e., anti-ICOS antibodies combined with otheragents. For example, the combination therapy can include an anti-ICOSantibody described herein combined with at least one other anti-cancerand/or T-cell stimulating (e.g., activating) agent. Examples oftherapeutic agents that can be used in combination therapy are describedin greater detail below in the section on uses of the antibodiesdescribed herein.

In some embodiments, pharmaceutical compositions disclosed herein caninclude other compounds, drugs, and/or agents used for the treatment ofcancer. Such compounds, drugs, and/or agents can include, for example,chemotherapy drugs, small molecule drugs or antibodies that stimulatethe immune response to a given cancer. In some embodiments, apharmaceutical composition comprises a first antibody specific foranti-huICOS and a second antibody.

In some embodiments, the first antibody and the second antibody arepresent in the composition at a fixed dose (i.e., a fixed ratio). Inother embodiments, this fixed dose is between at least about 1:200 to atleast about 200:1, at least about 1:150 to at least about 150:1, atleast about 1:100 to at least about 100:1, at least about 1:75 to atleast about 75:1, at least about 1:50 to at least about 50:1, at leastabout 1:25 to at least about 25:1, at least about 1:10 to at least about10:1, at least about 1:5 to at least about 5:1, at least about 1:4 to atleast about 4:1, at least about 1:3 to at least about 3:1, or at leastabout 1:2 to at least about 2:1 mg anti-huICOS antibody to mg secondantibody. In some embodiments, the fixed dose is at least about 1:1,about 1:2, about 1:3, about 1:4, about 1:5, about 1:6, about 1:7, about1:8, about 1:9, about 1:10, about 1:15, about 1:20, about 1:30, about1:40, about 1:50, about 1:60, about 1:70, about 1:80, about 1:90, about1:100, about 1:120, about 1:140, about 1:160, about 1:180, or about1:200 anti-huICOS antibody to second antibody. In some embodiments, thefixed dose is at least about 2:1, about 3:1, about 4:1, about 5:1, about6:1, about 7:1, about 8:1, about 9:1, about 10:1, about 15:1, about20:1, about 30:1, about 40:1, about 50:1, about 60:1, about 70:1, about80:1, about 90:1, about 100:1, about 120:1, about 140:1, about 160:1,about 180:1, or about 200:1 mg first antibody to mg second antibody. Forexample, in one embodiment, the anti-huICOS antibody and the secondantibody are administered as described in Example 18.

The additional antibodies include, for example, one or more of ananti-CTLA-4 antibody, an anti-PD-1 antibody, an anti-PD-L1 antibody, ananti-TIGIT antibody, an anti-OX40 (also known as CD134, TNFRSF4, ACT35and/or TXGP1L) antibody, an anti-LAG-3 antibody, an anti-CD73 antibody,an anti-CD137 antibody, an anti-CD27 antibody, or an anti-CSF-1Rantibody.

As used herein, “pharmaceutically acceptable carrier” includes any andall solvents, dispersion media, coatings, antibacterial and antifungalagents, isotonic and absorption delaying agents, and the like that arephysiologically compatible. In some embodiments, the carrier is suitablefor intravenous, intramuscular, subcutaneous, parenteral, spinal orepidermal administration (e.g., by injection or infusion). In someembodiments, the carrier is suitable for intravenous administration. Inother embodiments, the carrier is suitable for subcutaneousadministration. In some embodiments, the composition comprisinganti-ICOS antibody is delivered subcutaneously using Halozyme's ENHANZE®drug delivery technology, which includes a recombinant humanhyaluronidase enzyme (rHuPH20) that temporarily degrades hyaluronan. Insome embodiments, the ENHANZE® drug delivery technology allows forsubcutaneous administrations of compositions that is more rapid ascompared to intravenous administration. In other embodiments, dependingon the route of administration, the active compound, i.e., antibody,immunoconjugate, or bispecific molecule, may be coated in a material toprotect the compound from the action of acids and other naturalconditions that may inactivate the compound.

The pharmaceutical compounds described herein may include one or morepharmaceutically acceptable salts. A “pharmaceutically acceptable salt”refers to a salt that retains the desired biological activity of theparent compound and does not impart any undesired toxicological effects(see e.g., Berge, S. M., et al. (1977)J. Pharm. Sci. 66:1-19). Examplesof such salts include acid addition salts and base addition salts. Acidaddition salts include those derived from nontoxic inorganic acids, suchas hydrochloric, nitric, phosphoric, sulfuric, hydrobromic, hydroiodic,phosphorous and the like, as well as from nontoxic organic acids such asaliphatic mono- and dicarboxylic acids, phenyl-substituted alkanoicacids, hydroxy alkanoic acids, aromatic acids, aliphatic and aromaticsulfonic acids and the like. Base addition salts include those derivedfrom alkaline earth metals, such as sodium, potassium, magnesium,calcium and the like, as well as from nontoxic organic amines, such asN,N′-dibenzylethylenediamine, N-methylglucamine, chloroprocaine,choline, diethanolamine, ethylenediamine, procaine and the like.

A pharmaceutical composition described herein also may include apharmaceutically acceptable anti-oxidant. Examples of pharmaceuticallyacceptable antioxidants include: (1) water soluble antioxidants, such asascorbic acid, cysteine hydrochloride, sodium bisulfate, sodiummetabisulfite, sodium sulfite and the like; (2) oil-solubleantioxidants, such as ascorbyl palmitate, butylated hydroxyanisole(BHA), butylated hydroxytoluene (BHT), lecithin, propyl gallate,alpha-tocopherol, and the like; and (3) metal chelating agents, such ascitric acid, ethylenediamine tetraacetic acid (EDTA), sorbitol, tartaricacid, phosphoric acid, and the like.

Examples of suitable aqueous and non-aqueous carriers that may beemployed in the pharmaceutical compositions described herein includewater, ethanol, polyols (such as glycerol, propylene glycol,polyethylene glycol, and the like), and suitable mixtures thereof,vegetable oils, such as olive oil, and injectable organic esters, suchas ethyl oleate. Proper fluidity can be maintained, for example, by theuse of coating materials, such as lecithin, by the maintenance of therequired particle size in the case of dispersions, and by the use ofsurfactants.

These compositions may also contain adjuvants such as preservatives,wetting agents, emulsifying agents and dispersing agents. Prevention ofpresence of microorganisms may be ensured both by sterilizationprocedures, supra, and by the inclusion of various antibacterial andantifungal agents, for example, paraben, chlorobutanol, phenol sorbicacid, and the like. It may also be desirable to include isotonic agents,such as sugars, sodium chloride, and the like into the compositions. Inaddition, prolonged absorption of the injectable pharmaceutical form maybe brought about by the inclusion of agents that delay absorption suchas aluminum monostearate and gelatin.

Pharmaceutically acceptable carriers include sterile aqueous solutionsor dispersions and sterile powders for the extemporaneous preparation ofsterile injectable solutions or dispersion. Exemplary pharmaceuticallyacceptable carriers herein further include interstitial drug dispersionagents such as soluble neutral-active hyaluronidase glycoproteins(sHASEGP), for example, human soluble PH-20 hyaluronidase glycoproteins,such as rHuPH20 (HYLENEX™, Baxter International, Inc.). Certainexemplary sHASEGPs and methods of use, including rHuPH20, are describedin US Patent Publication Nos. 2005/0260186 and 2006/0104968. In oneaspect, a sHASEGP is combined with one or more additionalglycosaminoglycanases such as chondroitinases.

The use of such media and agents for pharmaceutically active substancesis known in the art. Except insofar as any conventional media or agentis incompatible with the active compound, use thereof in thepharmaceutical compositions described herein is contemplated.Supplementary active compounds can also be incorporated into thecompositions.

Therapeutic compositions typically must be sterile and stable under theconditions of manufacture and storage. The composition can be formulatedas a solution, microemulsion, liposome, or other ordered structuresuitable to high drug concentration. The carrier can be a solvent ordispersion medium containing, for example, water, ethanol, polyol (forexample, glycerol, propylene glycol, and liquid polyethylene glycol, andthe like), and suitable mixtures thereof. The proper fluidity can bemaintained, for example, by the use of a coating such as lecithin, bythe maintenance of the required particle size in the case of dispersionand by the use of surfactants. In many cases, it will be preferable toinclude isotonic agents, for example, sugars, polyalcohols such asmannitol, sorbitol, or sodium chloride in the composition. Prolongedabsorption of the injectable compositions can be brought about byincluding in the composition an agent that delays absorption, forexample, monostearate salts and gelatin.

Sterile injectable solutions can be prepared by incorporating the activecompound in the required amount in an appropriate solvent with one or acombination of ingredients enumerated above, as required, followed bysterilization microfiltration. Generally, dispersions are prepared byincorporating the active compound into a sterile vehicle that contains abasic dispersion medium and the required other ingredients from thosedescribed above. In the case of sterile powders for the preparation ofsterile injectable solutions, the preferred methods of preparation arevacuum drying and freeze-drying (lyophilization) that yield a powder ofthe active ingredient plus any additional desired ingredient from apreviously sterile-filtered solution thereof.

The amount of active ingredient that can be combined with a carriermaterial to produce a single dosage form will vary depending upon thesubject being treated, and the particular mode of administration. Theamount of active ingredient that can be combined with a carrier materialto produce a single dosage form will generally be that amount of thecomposition that produces a therapeutic effect. Out of one hundredpercent, this amount may range from about 0.01 percent to aboutninety-nine percent of active ingredient, e.g., from about 0.1 percentto about 70 percent, e.g., from about 1 percent to about 30 percent ofactive ingredient in combination with a pharmaceutically acceptablecarrier.

In some embodiments, the composition includes an anti-ICOS antibody,such as the ICOS.33 IgG1f S267E antibody, at a concentration of 10mg/mL. The composition is a sterile, non-pyrogenic, single-use,preservative-free, isotonic aqueous solution for intravenousadministration. The composition may be administered undiluted or furtherdiluted with 0.9% sodium chloride injection to the required proteinconcentrations prior to infusion. In some embodiments, the anti-ICOSantibody includes the following excipients: L-histine, L-histidinehydrochloride monohydrate, sucrose, pentetic acid (also known asdiethylenetriaminepentaaceitc acid, polysorbate 80, and water for theinjection.

Dosage regimens are adjusted to provide the optimum desired response(e.g., a therapeutic response). For example, a single bolus may beadministered, several divided doses may be administered over time or thedose may be proportionally reduced or increased as indicated by theexigencies of the therapeutic situation. It is especially advantageousto formulate parenteral compositions in dosage unit form for ease ofadministration and uniformity of dosage. Dosage unit form as used hereinrefers to physically discrete units suited as unitary dosages for thesubjects to be treated; each unit contains a predetermined quantity ofactive compound calculated to produce the desired therapeutic effect inassociation with the required pharmaceutical carrier. The specificationfor the dosage unit forms described herein are dictated by and directlydependent on (a) the unique characteristics of the active compound andthe particular therapeutic effect to be achieved, and (b) thelimitations inherent in the art of compounding such an active compoundfor the treatment of sensitivity in individuals.

For administration of the antibody, the dosage may range from about0.0001 to 100 mg/kg, and more usually 0.01 to 5 mg/kg, of the host bodyweight. For example, dosages can be 0.3 mg/kg body weight, 1 mg/kg bodyweight, 3 mg/kg body weight, 5 mg/kg body weight or 10 mg/kg body weightor within the range of 1-10 mg/kg. Alternatively, administration of theantibody is a flat dose which may range from 2 mg to 800 mg, forexample, a dose of 25 mg, 80 mg, 200 mg, or 400 mg. An exemplarytreatment regimen entails administration once per week, once every twoweeks, once every three weeks, once every four weeks, once a month, onceevery two months, once every three months, once every four months, onceevery five months, or once every six months. In some embodiments, thetreatment regimen includes an initial dose, and then a maintenance doseof a different dose amount at an intermittent dose interval.

In some embodiments, two or more monoclonal antibodies with differentbinding specificities are administered simultaneously, in which case thedosage of each antibody administered falls within the ranges indicated.In some embodiments, the therapeutic antibody is administered onmultiple occasions. Intervals between single dosages can be, forexample, weekly, once every three weeks, once every four weeks, monthly,every three months or yearly. Intervals can also be irregular asindicated by measuring blood levels of antibody to the target antigen inthe patient. In some embodiments, dosage is adjusted to achieve a plasmaantibody concentration of about 1-1000 μg/ml and in some methods about25-300 μg/ml.

In some embodiments, the antibody can be administered as a sustainedrelease formulation. Administration via a sustained release formulationsmight require less frequent administration. Dosage and frequency varydepending on the half-life of the antibody in the patient. The dosageand frequency of administration can vary depending on whether thetreatment is prophylactic or therapeutic. In prophylactic applications,a relatively low dosage is administered at relatively infrequentintervals over a long period of time. Some patients continue to receivetreatment for the rest of their lives. In some embodiments, a relativelyhigh dosage at relatively short intervals is administered fortherapeutic treatment. In some embodiments, a relatively high dosage isadministered until progression of the disease is reduced or terminated,e.g., until the patient shows partial or complete amelioration ofsymptoms of disease. In some embodiments, a prophylactic treatment isadministered to patient following a therapeutic treatment.

Actual dosage levels of the active ingredients in the pharmaceuticalcompositions described herein may be varied so as to obtain an amount ofthe active ingredient that is effective to achieve the desiredtherapeutic response for a particular patient, composition, and mode ofadministration, without being toxic to the patient. The selected dosagelevel will depend upon a variety of pharmacokinetic factors includingthe activity of the particular compositions described herein employed,or the ester, salt or amide thereof, the route of administration, thetime of administration, the rate of excretion of the particular compoundbeing employed, the duration of the treatment, other drugs, compoundsand/or materials used in combination with the particular compositionsemployed, the age, sex, weight, condition, general health and priormedical history of the patient being treated, and like factors wellknown in the medical arts.

A “therapeutically effective dosage” of an anti-ICOS antibody describedherein preferably results in a decrease in severity of disease symptoms,an increase in frequency and duration of disease symptom-free periods,or a prevention of impairment or disability due to the diseaseaffliction. In the context of cancer, a therapeutically effective dosepreferably prevents further deterioration of physical symptomsassociated with cancer. Symptoms of cancer are well-known in the art andinclude, for example, unusual mole features, a change in the appearanceof a mole, including asymmetry, border, color and/or diameter, a newlypigmented skin area, an abnormal mole, darkened area under nail, breastlumps, nipple changes, breast cysts, breast pain, death, weight loss,weakness, excessive fatigue, difficulty eating, loss of appetite,chronic cough, worsening breathlessness, coughing up blood, blood in theurine, blood in stool, nausea, vomiting, liver metastases, lungmetastases, bone metastases, abdominal fullness, bloating, fluid inperitoneal cavity, vaginal bleeding, constipation, abdominal distension,perforation of colon, acute peritonitis (infection, fever, pain), pain,vomiting blood, heavy sweating, fever, high blood pressure, anemia,diarrhea, jaundice, dizziness, chills, muscle spasms, colon metastases,lung metastases, bladder metastases, liver metastases, bone metastases,kidney metastases, and pancreatic metastases, difficulty swallowing, andthe like. Therapeutic efficacy may be observable immediately after thefirst administration of an agonistic anti-huICOS monoclonal antibody ofthe present invention, or it may only be observed after a period of timeand/or a series of doses. Such delayed efficacy my only be observedafter several months of treatment, e.g., up to 6, 9 or 12 months.

A therapeutically effective dose may prevent or delay onset of cancer,such as may be desired when early or preliminary signs of the diseaseare present. Accordingly, any clinical or biochemical assay thatmonitors any of the foregoing may be used to determine whether aparticular treatment is a therapeutically effective dose for treatingcancer. One of ordinary skill in the art would be able to determine suchamounts based on such factors as the subject's size, the severity of thesubject's symptoms, and the particular composition or route ofadministration selected.

A composition described herein can be administered via one or moreroutes of administration using one or more of a variety of methods knownin the art. As will be appreciated by the skilled artisan, the routeand/or mode of administration will vary depending upon the desiredresults. Exemplary routes of administration for antibodies describedherein include intravenous, intramuscular, intradermal, intraperitoneal,subcutaneous, spinal or other parenteral routes of administration, forexample by injection or infusion.

Alternatively, an antibody described herein can be administered via anon-parenteral route, such as a topical, epidermal or mucosal route ofadministration, for example, intranasally, orally, vaginally, rectally,sublingually or topically.

The active compounds can be prepared with carriers that will protect thecompound against rapid release, such as a controlled releaseformulation, including implants, transdermal patches, andmicroencapsulated delivery systems. Biodegradable, biocompatiblepolymers can be used, such as ethylene vinyl acetate, polyanhydrides,polyglycolic acid, collagen, polyorthoesters, and polylactic acid. Manymethods for the preparation of such formulations are patented orgenerally known to those skilled in the art. See, e.g., Sustained andControlled Release Drug Delivery Systems, J. R. Robinson, ed., MarcelDekker, Inc., New York, 1978.

Therapeutic compositions can be administered with medical devices knownin the art. For example, in a preferred embodiment, a therapeuticcomposition described herein can be administered with a needlelesshypodermic injection device, such as the devices disclosed in U.S. Pat.Nos. 5,399,163; 5,383,851; 5,312,335; 5,064,413; 4,941,880; 4,790,824;or 4,596,556. Examples of well-known implants and modules for use withanti-huICOS antibodies described herein include: U.S. Pat. No.4,487,603, which discloses an implantable micro-infusion pump fordispensing medication at a controlled rate; U.S. Pat. No. 4,486,194,which discloses a therapeutic device for administering medicamentsthrough the skin; U.S. Pat. No. 4,447,233, which discloses a medicationinfusion pump for delivering medication at a precise infusion rate; U.S.Pat. No. 4,447,224, which discloses a variable flow implantable infusionapparatus for continuous drug delivery; U.S. Pat. No. 4,439,196, whichdiscloses an osmotic drug delivery system having multi-chambercompartments; and U.S. Pat. No. 4,475,196, which discloses an osmoticdrug delivery system. These patents are incorporated herein byreference. Many other such implants, delivery systems, and modules areknown to those skilled in the art.

In certain embodiments, the anti-huICOS antibodies described herein canbe formulated to ensure proper distribution in vivo. For example, theblood-brain barrier (BBB) excludes many highly hydrophilic compounds. Toensure that the therapeutic compounds described herein cross the BBB (ifdesired), they can be formulated, for example, in liposomes. For methodsof manufacturing liposomes, see, e.g., U.S. Pat. Nos. 4,522,811;5,374,548; and 5,399,331. The liposomes may comprise one or moremoieties that are selectively transported into specific cells or organs,thus enhance targeted drug delivery (see, e.g., V. V. Ranade (1989) J.Clin. Pharmacol. 29:685). Exemplary targeting moieties include folate orbiotin (see, e.g., U.S. Pat. No. 5,416,016 to Low et al.); mannosides(Umezawa et al., (1988) Biochem. Biophys. Res. Commun. 153:1038);antibodies (P. G. Bloeman et al. (1995) FEBS Lett. 357:140; M. Owais etal. (1995) Antimicrob. Agents Chemother. 39:180); surfactant protein Areceptor (Briscoe et al. (1995) Am. J. Physiol. 1233:134); p120(Schreier et al. (1994) J. Biol. Chem. 269:9090); see also K. Keinanen;M. L. Laukkanen (1994) FEBS Lett. 346:123; J. J. Killion; I. J. Fidler(1994) Immunomethods 4:273.

Also within the scope described herein are kits comprising the antibodycompositions described herein (e.g., human antibodies, bispecific ormultispecific molecules, or immunoconjugates) and instructions for use.The kit can further contain at least one additional reagent, or one ormore additional human antibodies described herein. Kits can include alabel indicating the intended use of the contents of the kit. The termlabel includes any writing, or recorded material supplied on or with thekit, or that otherwise accompanies the kit.

X. Methods of Use

The antibodies, antibody compositions and methods described herein havenumerous in vitro and in vivo uses involving, for example, enhancementof immune response by stimulating ICOS signaling. In one embodiment, theantibodies described herein are monoclonal human or humanizedantibodies. In one embodiment, anti-huICOS antibodies described herein(e.g., ICOS.33 IgG1f S267E, 17C4, 9D5, 3E8, 1D7, and 2644) can beadministered to cells in culture, in vitro or ex vivo, or to humansubjects to enhance immunity in a variety of diseases. In a particularembodiment, the anti-huICOS antibodies agonistic antibodies, i.e.,agonist anti-huICOS antibodies. Provided herein are methods of modifyingan immune response in a subject comprising administering to the subjectan antibody, or antigen-binding fragment thereof, described herein suchthat the immune response in the subject is enhanced, stimulated orup-regulated. In one embodiment, administering the anti-huICOS antibody(i.e., the agonist anti-huICOS antibody) according to the methodsdescribed herein enhances co-stimulation of T cell responses. In oneembodiment, administering the anti-huICOS antibody according to themethods described herein stimulates, enhances or upregulatesantigen-specific T cell responses to a tumor. A tumor may be a solidtumor or a liquid tumor, e.g., a hematological malignancy. In certainembodiments, a tumor is an immunogenic tumor. In certain embodiments, atumor is non-immunogenic. In certain embodiments, a tumor is PD-L1positive. In certain embodiments a tumor is PD-L1 negative. A subjectmay also be a virus-bearing subject and an immune response against thevirus is enhanced. In one embodiment, administering the anti-huICOSantibody according to the methods described herein stimulates, enhancesor upregulates CD4+ and CD8+ T cell responses. The T cells can be Teffcells, e.g., CD4+ Teff cells, CD8+ Teff cells, T helper (T_(h)) cellsand T cytotoxic (T_(c)) cells.

In one embodiment, the methods result in an enhancement of an immuneresponse in a human subject wherein such enhancement has a desirableeffect. In one embodiment, the human subject is a human patients havinga disorder that can be treated by augmenting an immune response, e.g.,the T-cell mediated immune response. In a particular embodiment, thehuman patient has a cancer. In one embodiment, anti-huICOS antibodiesdescribed herein can be administered together with an antigen ofinterest or the antigen may already be present in the subject to betreated, e.g., a tumor-bearing or virus-bearing subject. When antibodiesto ICOS are administered together with another agent, the two can beadministered separately or simultaneously.

Further provided are methods for inhibiting growth of a tumor cell in asubject comprising administering to the subject an anti-huICOS antibodydescribed herein such that growth of the tumor cell is inhibited in thesubject. Also provided are methods of treating chronic viral infectionin a subject comprising administering to the subject an anti-huICOSantibody described herein such that the chronic viral infection istreated in the subject.

In some embodiments, an anti-huICOS agonist antibody is administered toa subject, e.g., a human patient, as an adjunctive therapy, adjuvanttherapy, or neo-adjuvant therapy. In some embodiments, treatments ofsubjects having cancer with an anti-huICOS antibody may lead to along-term durable response relative to the current standard of care;long term survival of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or moreyears, recurrence free survival of at least 1, 2, 3, 4, 5, 6, 7, 8, 9,or 10 or more years. In certain embodiments, treatment of a subjecthaving cancer with an anti-huICOS antibody prevents recurrence of canceror delays recurrence of cancer by, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or10 or more years. An anti-ICOS treatment can be used as a first, second,or subsequent line of treatment.

These and other methods described herein are discussed in further detailbelow.

Cancer

Provided herein are methods for treating a subject having cancer,comprising administering to the subject an anti-huICOS antibodydescribed herein, such that the subject is treated, e.g., such thatgrowth of cancerous tumors is inhibited or reduced and/or that thetumors regress. An anti-huICOS antibody can be used alone to inhibit thegrowth of cancerous tumors. Alternatively, an anti-huICOS antibody canbe used in conjunction with another agent, e.g., other immunogenicagents, standard cancer treatments, or other antibodies, as describedbelow. Combination with an inhibitor of PD-1, such as an anti-PD-1 or ananti-PD-L1 antibody, is also provided. Combination with an inhibitor ofCTLA-4, such as an anti-CTLA-4 antibody, is also provided. Combinationwith an inhibitor of PD-1 and an inhibitor of CTLA-4 is also provided.

In one aspect, provided herein are methods of treating cancer in asubject, comprising administering to the subject a therapeuticallyeffective amount of an anti-huICOS antibody described herein, e.g., ahumanized form of a hamster anti-ICOS antibody or antigen-bindingfragment thereof. In one embodiment, the anti-huICOS antibody may be achimeric antibody, a human antibody, or a humanized anti-huICOSantibody, e.g., any of the humanized anti-huICOS antibodies describedherein. In one embodiment, the methods of treating a cancer describedherein comprise administering a humanized anti-huICOS antibody thatcontacts human ICOS at one or more amino acid residues of SEQ ID NO: 203of human ICOS protein. In another embodiment, the method comprisesadministering ICOS.33 IgG1f S267E antibody. In another embodiment, themethod comprises administering a composition comprising ICOS.33 IgG1fS267E antibody.

Examples of cancer include, but are not limited to, squamous cellcarcinoma, small-cell lung cancer (SCLC), non-small cell lung cancer,squamous non-small cell lung cancer (NSCLC), non NSCLC, glioma,gastrointestinal cancer, renal cancer (e.g. clear cell carcinoma),ovarian cancer, liver cancer, colorectal cancer, endometrial cancer,kidney cancer (e.g., renal cell carcinoma (RCC)), prostate cancer (e.g.hormone refractory prostate adenocarcinoma), thyroid cancer,neuroblastoma, pancreatic cancer, glioblastoma (glioblastomamultiforme), cervical cancer, stomach cancer, bladder cancer, hepatoma,breast cancer, colon carcinoma, and head and neck cancer (or carcinoma),gastric cancer, germ cell tumor, pediatric sarcoma, sinonasal naturalkiller, melanoma (e.g., metastatic malignant melanoma, such as cutaneousor intraocular malignant melanoma), bone cancer, skin cancer, uterinecancer, cancer of the anal region, testicular cancer, carcinoma of thefallopian tubes, carcinoma of the endometrium, carcinoma of the cervix,carcinoma of the vagina, carcinoma of the vulva, cancer of theesophagus, cancer of the small intestine, cancer of the endocrinesystem, cancer of the parathyroid gland, cancer of the adrenal gland,sarcoma of soft tissue, cancer of the urethra, cancer of the penis,solid tumors of childhood, cancer of the ureter, carcinoma of the renalpelvis, neoplasm of the central nervous system (CNS), primary CNSlymphoma, tumor angiogenesis, spinal axis tumor, brain cancer includingbrain stem glioma, pituitary adenoma, Kaposi's sarcoma, epidermoidcancer, squamous cell cancer, T-cell lymphoma, environmentally-inducedcancers including those induced by asbestos, virus-related cancers(e.g., human papilloma virus (HPV)-related tumor), and hematologicmalignancies derived from either of the two major blood cell lineages,i.e., the myeloid cell line (which produces granulocytes, erythrocytes,thrombocytes, macrophages, and mast cells) or lymphoid cell line (whichproduces B, T, NK, and plasma cells), such as all types of leukemias,lymphomas, and myelomas, e.g., acute, chronic, lymphocytic and/ormyelogenous leukemias, such as acute leukemia (ALL), acute myelogenousleukemia (AML), chronic lymphocytic leukemia (CLL), and chronicmyelogenous leukemia (CML), undifferentiated AML (M0), myeloblasticleukemia (M1), myeloblastic leukemia (M2; with cell maturation),promyelocytic leukemia (M3 or M3 variant [M3V]), myelomonocytic leukemia(M4 or M4 variant with eosinophilia [M4E]), monocytic leukemia (M5),erythroleukemia (M6), megakaryoblastic leukemia (M7), isolatedgranulocytic sarcoma, and chloroma; lymphomas, such as Hodgkin'slymphoma (HL), non-Hodgkin's lymphoma (NHL), B-cell lymphomas, T-celllymphomas, lymphoplasmacytoid lymphoma, monocytoid B-cell lymphoma,mucosa-associated lymphoid tissue (MALT) lymphoma, anaplastic (e.g., Ki1+) large-cell lymphoma, adult T-cell lymphoma/leukemia, mantle celllymphoma, angio immunoblastic T-cell lymphoma, angiocentric lymphoma,intestinal T-cell lymphoma, primary mediastinal B-cell lymphoma,precursor T-lymphoblastic lymphoma, T-lymphoblastic; andlymphoma/leukemia (T-Lbly/T-ALL), peripheral T-cell lymphoma,lymphoblastic lymphoma, post-transplantation lymphoproliferativedisorder, true histiocytic lymphoma, primary central nervous systemlymphoma, primary effusion lymphoma, lymphoblastic lymphoma (LBL),hematopoietic tumors of lymphoid lineage, acute lymphoblastic leukemia,diffuse large B-cell lymphoma, Burkitt's lymphoma, follicular lymphoma,diffuse histiocytic lymphoma (DHL), immunoblastic large cell lymphoma,precursor B-lymphoblastic lymphoma, cutaneous T-cell lymphoma (CTLC)(also called mycosis fungoides or Sezary syndrome), andlymphoplasmacytoid lymphoma (LPL) with Waldenstrom's macroglobulinemia;myelomas, such as IgG myeloma, light chain myeloma, nonsecretorymyeloma, smoldering myeloma (also called indolent myeloma), solitaryplasmocytoma, and multiple myelomas, chronic lymphocytic leukemia (CLL),hairy cell lymphoma; hematopoietic tumors of myeloid lineage, tumors ofmesenchymal origin, including fibrosarcoma and rhabdomyoscarcoma;seminoma, teratocarcinoma, tumors of the central and peripheral nervous,including astrocytoma, schwannomas; tumors of mesenchymal origin,including fibrosarcoma, rhabdomyoscaroma, and osteosarcoma; and othertumors, including melanoma, xeroderma pigmentosum, keratoacanthoma,seminoma, thyroid follicular cancer and teratocarcinoma, hematopoietictumors of lymphoid lineage, for example T-cell and B-cell tumors,including but not limited to T-cell disorders such as T-prolymphocyticleukemia (T-PLL), including of the small cell and cerebriform cell type;large granular lymphocyte leukemia (LGL) preferably of the T-cell type;a/d T-NHL hepatosplenic lymphoma; peripheral/post-thymic T cell lymphoma(pleomorphic and immunoblastic subtypes); angiocentric (nasal) T-celllymphoma; cancer of the head or neck, renal cancer, rectal cancer,cancer of the thyroid gland; acute myeloid lymphoma, as well as anycombinations of said cancers. In one embodiment, the methods describedherein may also be used for treatment of metastatic cancers, refractorycancers (e.g., cancers refractory to previous immunotherapy, e.g., witha blocking CTLA-4 and/or PD-1 antibody), and recurrent cancers.

In one embodiment, the anti-huICOS antibody may be administered as amonotherapy. In one embodiment, the anti-huICOS agonist antibody isadministered as the only immunostimulating agent. In one embodiment, theanti-human ICOS agonist antibody is administered to a patient withanother agent. In one embodiment, an anti-huICOS antibody isadministered with an immunogenic agent. In one embodiment, theanti-human ICOS agonist antibody is administered in conjunction with acancer vaccine. In some embodiments, the cancer vaccine comprisescancerous cells, purified tumor antigens (including recombinantproteins, peptides, and carbohydrate molecules), cells, and cellstransfected with genes encoding immune stimulating cytokines (He et al.(2004) J. Immunol. 173:4919-28). In some embodiments, the cancer vaccineis a peptide cancer vaccine, which in some embodiments is a personalizedpeptide vaccine. In some embodiments the peptide cancer vaccine is amultivalent long peptide, a multi-peptide, a peptide cocktail, a hybridpeptide, or a peptide-pulsed dendritic cell vaccine (see, e.g., Yamadaet al., Cancer Sci, 104:14-21, 2013). In some embodiments, an anti-humanICOS agonist antibody may be administered in conjunction with anadjuvant. Non-limiting examples of tumor vaccines that can be usedinclude peptides of melanoma antigens, such as peptides of gp 100, MAGEantigens, Trp-2, MART 1 and/or tyrosinase, or tumor cells transfected toexpress the cytokine GM-CSF. Many experimental strategies forvaccination against tumors have been devised (see Rosenberg, S., 2000,Development of Cancer Vaccines, ASCO Educational Book Spring: 60-62;Logothetis, C., 2000, ASCO Educational Book Spring: 300-302; Khayat, D.2000, ASCO Educational Book Spring: 414-428; Foon, K. 2000, ASCOEducational Book Spring: 730-738; see also Restifo, N. and Sznol, M.,Cancer Vaccines, Ch. 61, pp. 3023-3043 in DeVita et al. (eds.), 1997,Cancer: Principles and Practice of Oncology, Fifth Edition). In one ofthese strategies, a vaccine is prepared using autologous or allogeneictumor cells. These cellular vaccines have been shown to be mosteffective when the tumor cells are transduced to express GM-CSF. GM-CSFhas been shown to be a potent activator of antigen presentation fortumor vaccination. Dranoff et al. (1993) Proc. Natl. Acad. Sci. U.S.A.90: 3539-43.

Other cancer vaccines can include the proteins from viruses implicatedin human cancers such a Human Papilloma Viruses (HPV), Hepatitis Viruses(HBV and HCV) and Kaposi's Herpes Sarcoma Virus (KHSV). Another form oftumor specific antigen that can be used in conjunction with ICOSinhibition is purified heat shock proteins (HSP) isolated from the tumortissue itself. These heat shock proteins contain fragments of proteinsfrom the tumor cells and these HSPs are highly efficient at delivery toantigen presenting cells for eliciting tumor immunity (Suot & Srivastava(1995) Science 269:1585-1588; Tamura et al. (1997) Science 278:117-120).

Dendritic cells are potent antigen presenting cells that can be used toprime antigen-specific responses. Dendritic cells can be produced exvivo and loaded with various protein and peptide antigens as well astumor cell extracts (Nestle et al. (1998) Nature Medicine 4: 328-332).Dendritic cells can also be transduced by genetic means to express thesetumor antigens as well. DCs have also been fused directly to tumor cellsfor the purposes of immunization (Kugler et al. (2000) Nature Medicine6:332-336). As a method of vaccination, Dendritic cell immunization canbe effectively combined with ICOS agonism to activate (unleash) morepotent anti-tumor responses.

In some embodiments, an anti-human ICOS agonist antibody is administeredin conjunction with standard of care, e.g., surgery, radiation, and/orchemotherapy. In some embodiments, an anti-ICOS antibody may beadministered in conjunction with a chemotherapeutic agent. In someembodiments, the anti-ICOS antibody is administered in conjunction withone or more of carboplatin, cisplatin, paclitaxel, nab-paclitaxel,gemcitabine or FOLFOX. In some embodiment, an anti-human ICOS agonistantibody may be administered in conjunction with carboplatin ornab-paclitaxel. In some embodiments, an anti-human ICOS agonist antibodymay be administered in conjunction with carboplatin and paclitaxel. Insome embodiments, an anti-human ICOS agonist antibody may beadministered in conjunction with cisplatin and pemetrexed. In someembodiments, an anti-human ICOS agonist antibody may be administered inconjunction with cisplatin and gemcitabine. In some embodiments, ananti-human ICOS agonist antibody may be administered in conjunction withFOLFOX. In some embodiments, an anti-human ICOS agonist antibody may beadministered in conjunction with FOLFIRI. In one embodiment, ananti-huICOS antibody is administered in combination with decarbazine forthe treatment of melanoma. In some embodiments, cisplatin isintravenously administered as a 100 mg/ml dose once every four weeks. Insome embodiments, an anti-human ICOS agonist antibody may beadministered in conjunction with doxorubicin (adriamycin), cisplatinbleomycin sulfate, carmustine, chlorambucil, dacarbazine and/orcyclophosphamide hydroxyurea. In some embodiments, adriamycin isintravenously administered as a 60 mg/ml to 75 mg/ml dose once every 21days. In one embodiment, the anti-huICOS antibody is administered to ahuman patient that is resistant to treatment with at least one drugs,wherein administration of the anti-huICOS antibody reduces, alleviates,or abrogates resistance to the at least one drug.

The combination therapies noted above encompass combined administration(where two or more therapeutic agents are included in the same orseparate formulations), and separate administration, in which case,administration of the antibody of the invention can occur prior to,simultaneously, and/or following, administration of the additionaltherapeutic agent and/or adjuvant. Antibodies of the invention can alsobe used in combination with radiation therapy.

Another example of such a combination is an anti-huICOS antibody incombination with interleukin-2 (IL-2). In some embodiments, thecombination of anti-huICOS antibody and IL-2 is to treat variouscancers, including for the treatment of renal cell carcinoma andmelanoma. In some embodiments, the anti-huICOS antibodies discussedherein is combined with an IL-2 pathway agonist to treat variouscancers. The combination includes various IL-2 pathway agonists, such asthose described in WO 2012/065086 (Nektar Therapeutics) and WO2015/125159 (Nektar Therapeutics), the contents of which areincorporated by reference in their entireties. WO 2006/138572 (NektarTherapeutics) provides conjugates having a degradable linkage andpolymeric reagents useful in preparing such conjugates, as well asmethods of making polymeric reagents and conjugates, and is incorporatedby reference in its entirety.

In some embodiments, the combination of an anti-huICOS antibody asdescribed herein, such as ICOS.33 IgG1 S267E, and an IL-2 pathwayagonist, such as NKTR-214, is administered to patients to treat cancer.As described in more detail below, NKTR-214 is produced by conjugatingon average around six FMOC (fluorenylmethyloxycarbonyl chloride)-basedpolyethylene glycol (PEG) reagents having the following structure(nmPEG₂-C2-fomc-20K-N-Hydroxysuccinimidate Derivative, 20 kDa,(“mPEG2-C2-fmoc-20K-NHS”):

to a protein having the following 132-amino acid sequence:

(SEQ ID NO: 219)PTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTRMLTFKFYMPKKATELKHLQCLEE 60ELKPLEEVLNLAQSKNFHLRPRDLISNINVIVLELKGSETTFMCEYADETATIVEFLNRW 120ITFSQSIISTLT 132

WO 2012/065086 provides conjugates of an IL-2 moiety and one or morenon-peptide, water-soluble polymers, including polyethylene glycol or aderivative thereof. Specifically, Example 2 (paragraphs 202-204) of WO2012/065086 describes PEGylation of rIL-2 with mPEG2-C2-fmoc-20K-NHS toresult in the mPEG2-C2-fmoc-20K-NHS structure set forth above. Example 1(paragraphs 63-66) WO 2015/125159 describes a scaled-up approach forPEGylating IL-2 with mPEG2-C2-fmoc-20K-NHS that results in RSLAIL-2(NKTR-214). NKTR-214 is a cytokine that is designed to target CD122,(also known as interleukin-2 receptor beta subunit, IL-2Rβ), a proteinfound on certain immune cells (e.g., CD8+ T Cells and NK Cells), toexpand these cells to promote their anti-tumor effects.

In some embodiments, an anti-huICOS antibody may be administered incombination with an anti-angiogenic agent.

Other combination therapies that may result in synergy with ICOS agonismthrough cell death are radiation, surgery, and hormone deprivation.

In some embodiments, anti-huICOS antibodies described herein may beadministered in conjunction with bispecific antibodies. Bispecificantibodies can be used to target two separate antigens. In oneembodiment, anti-huICOS antibodies are used in combination withbispecific antibodies that target Fcα or Fcγ receptor-expressingeffectors cells to tumor cells (see, e.g., U.S. Pat. Nos. 5,922,845 and5,837,243). For example, anti-Fc receptor/anti-tumor antigen (e.g.,Her-2/neu) bispecific antibodies have been used to target macrophages tosites of tumor. In one embodiment, the T cell arm of these responses isaugmented by agonism of ICOS with an anti-huICOS antibody.Alternatively, antigen may be delivered directly to DCs by the use ofbispecific antibodies that bind to tumor antigen and a dendritic cellspecific cell surface marker. In some embodiments, anti-huICOSantibodies are used in combination with antibodies that reduce orinactivate the immunosuppressive proteins expressed by a tumor, e.g.,anti-TGF-β antibodies, anti-IL-10 antibodies, and anti-Fas ligandantibodies.

Chronic Viral Infections

In another aspect, the invention described herein provides a method oftreating an infectious disease in a subject comprising administering tothe subject an anti-huICOS antibody, or antigen-binding fragmentthereof, such that the subject is treated for the infectious disease.

Similar to its application to tumors as discussed above,antibody-mediated ICOS agonism can be used alone, or as an adjuvant, incombination with vaccines, to enhance the immune response to pathogens,toxins, and self-antigens. Examples of pathogens for which thistherapeutic approach can be particularly useful, include pathogens forwhich there is currently no effective vaccine, or pathogens for whichconventional vaccines are less than completely effective. These include,but are not limited to HIV, Hepatitis (A, B, & C), Influenza, Herpes,Giardia, Malaria, Leishmania, Staphylococcus aureus, Pseudomonasaeruginosa. ICOS agonism is particularly useful against establishedinfections by agents such as human immunodeficiency virus (HIV) thatpresent altered antigens over the course of the infections. These novelepitopes are recognized as foreign at the time of anti-human ICOSantibody administration, thus provoking a strong T cell response.

Some examples of pathogenic viruses causing infections treatable bymethods described herein include HIV, hepatitis (A, B, or C), herpesvirus (e.g., VZV, HSV-1, HAV-6, HSV-II, and CMV, Epstein Barr virus),adenovirus, influenza virus, flaviviruses, echovirus, rhinovirus,coxsackie virus, coronavirus, respiratory syncytial virus, mumps virus,rotavirus, measles virus, rubella virus, parvovirus, vaccinia virus,HTLV virus, dengue virus, papillomavirus, molluscum virus, poliovirus,rabies virus, JC virus and arboviral encephalitis virus.

Some examples of pathogenic bacteria causing infections treatable bymethods described herein include chlamydia, rickettsial bacteria,mycobacteria, staphylococci, streptococci, pneumonococci, meningococciand gonococci, klebsiella, proteus, serratia, pseudomonas, legionella,diphtheria, salmonella, bacilli, cholera, tetanus, botulism, anthrax,plague, leptospirosis, and Lyme disease bacteria.

Some examples of pathogenic fungi causing infections treatable bymethods described herein include Candida (albicans, krusei, glabrata,tropicalis, etc.), Cryptococcus neoformans, Aspergillus (fumigatus,niger, etc.), Genus Mucorales (mucor, absidia, rhizopus), Sporothrixschenkii, Blastomyces dermatitidis, Paracoccidioides brasiliensis,Coccidioides immitis and Histoplasma capsulatum.

Some examples of pathogenic parasites causing infections treatable bymethods described herein include Entamoeba histolytica, Balantidiumcoli, Naegleriafowleri, Acanthamoeba sp., Giardia lambia,Cryptosporidium sp., Pneumocystis carinii, Plasmodium vivax, Babesiamicroti, Trypanosoma brucei, Trypanosoma cruzi, Leishmania donovani,Toxoplasma gondii, Nippostrongylus brasiliensis.

The methods described herein of administering anti-huICOS antibodies toa subject may be combined with other forms of immunotherapy such ascytokine treatment (e.g., interferons, GM-CSF, G-CSF, IL-2), orbispecific antibody therapy.

Combination Therapies

In one aspect, provided herein are methods of combination therapy, e.g.,for the treatment of cancer, in which an anti-huICOS antibody (e.g., anagonist anti-huICOS antibody) is administered in connection with one ormore additional agents, e.g., antibodies, that are effective instimulating immune responses to thereby further enhance, stimulate orupregulate immune responses in a subject. Provided herein are methodsfor treating or delaying progression of cancer in an individualcomprising administering to the individual an anti-huICOS antibody(e.g., ICOS.33 IgG1f S267E, 17C4, 9D5, 3E8, 1D7, and 2644) inconjunction with another anti-cancer agent or cancer therapy. In someembodiments, an anti-huICOS antibody may be administered in conjunctionwith a chemotherapy or chemotherapeutic agent or with a radiationtherapy or radiotherapeutic agent, as described above. In someembodiments, an anti-huICOS antibody may be administered in conjunction.In some embodiments, an anti-huICOS antibody may be administered inconjunction with a targeted therapy or targeted therapeutic agent. Insome embodiments, an anti-huICOS antibody may be administered inconjunction with an immunotherapy or immunotherapeutic agent, forexample a monoclonal antibody.

In some embodiments, an anti-huICOS antibody described herein can becombined with (i) an agonist of another co-stimulatory receptor and/or(ii) an antagonist of an inhibitory signal on T cells. In someembodiments, a combination therapy comprising an anti-huICOS antibodyand the agonist and/or antagonist results in an enhancedantigen-specific T cell response in a subject. In some embodiment,anti-ICOS antibodies described herein may be administered in conjunctionwith an agent that targets a co-stimulatory and co-inhibitory moleculesthat is a member of the immunoglobulin super family (IgSF) to increasean immune response. In some embodiment, anti-ICOS antibodies (e.g.,ICOS.33 IgG1f S267E, 17C4, 9D5, 3E8, 1D7, and 2644) described herein maybe administered in conjunction with an agent that targets a ligand of aco-stimulatory or co-inhibitory molecule. A family of membrane-boundligands that bind to co-stimulatory or co-inhibitory receptors is the B7family, which includes B7-1, B7-2, B7-H1 (PD-L1), B7-DC (PD-L2), B7-H2(ICOS-L), B7-H3, B7-H4, B7-H5 (VISTA), and B7-H6. Another family ofmembrane bound ligands that bind to co-stimulatory or co-inhibitoryreceptors is the TNF family of molecules that bind to cognate TNFreceptor family members, which include CD40, CD40L, OX-40, OX-40L, CD70,CD27L, CD30, CD30L, 4-1BBL, CD137/4-1BB, TRAIL/Apo2-L, TRAILR1/DR4,TRAILR2/DR5, TRAILR3, TRAILR4, OPG, RANK, RANKL, TWEAKR/Fn14, TWEAK,BAFFR, EDAR, XEDAR, TACI, APRIL, BCMA, LTβR, LIGHT, DcR3, HVEM,VEGI/TL1A, TRAMP/DR3, EDAR, EDA1, XEDAR, EDA2, TNFR1, Lymphotoxinα/TNFβ, TNFR2, TNFα, LTβR, Lymphotoxin α 1β2, FAS, FASL, RELT, DR6,TROY, NGFR.

In another aspect, anti-huICOS antibodies can be used in combinationwith antagonists of cytokines that inhibit T cell activation (e.g.,IL-6, IL-10, TGF-β, VEGF; or other “immunosuppressive cytokines,” orcytokines that stimulate T cell activation, for stimulating an immuneresponse, e.g., for treating proliferative diseases, such as cancer.

In one aspect, T cell responses are stimulated by a combination of ananti-huICOS antibody described herein and one or more of (i) anantagonist of a protein that inhibits T cell activation (e.g., immunecheckpoint inhibitors) such as CTLA-4, PD-1, PD-L1, PD-L2, LAG-3, TIM-3,Galectin 9, CEACAM-1, BTLA, CD69, Galectin-1, TIGIT, CD113, GPR56,VISTA, 2B4, CD48, GARP, PD1H, LAIR1, TIM-1, and TIM-4, and (ii) anagonist of a protein that stimulates T cell activation such as B7-1,B7-2, CD28, 4-1BB (CD137), 4-1BBL, CD40, ICOS-L, OX40, OX40L, GITR,GITRL, CD70, CD27, DR3 and CD28H.

Exemplary agents that modulate one of the above proteins and may becombined with agonist anti-huICOS antibodies, e.g., those describedherein, for treating cancer, include: YERVOY®/ipilimumab or tremelimumab(to CTLA-4), galiximab (to B7.1), BMS-936558 (to PD-1),pidilizumab/CT-011 (to PD-1), KEYTRUDA®/pembrolizumab/MK-3475 (to PD-1),AMP224 (to B7-DC/PD-L2), BMS-936559 (to B7-H1), MPDL3280A (to B7-H1),CP-870893 or dacetuzumab/SGN-40 (CD40—Kirkwood et al. (2012) CA CancerJ. Clin. 62:309; Vanderheide & Glennie (2013) Clin. Cancer Res.19:1035), AMG557 (to B7H2), MGA271 (to B7H3—WO 11/109400), IMP321 (toLAG-3), urelumab/BMS-663513 and PF-05082566 (to CD137/4-1BB),varlilumab/CDX-1127 (to CD27), MEDI-6383 and MEDI-6469 (to OX40),RG-7888 (to OX40L—WO 06/029879), Atacicept (to TACI), muromonab-CD3 (toCD3), ipilumumab (to CTLA-4). Accordingly, in one embodiment ananti-huICOS antibody (such as ICOS.33 IgG1f S267E) is combined with ananti-PD-1 antibody (such as nivolumab) and/or an anti-CTLA-4 antibody(such as ipilimumab).

Other molecules that can be combined with agonist anti-huICOS antibodiesfor the treatment of cancer include antagonists of inhibitory receptorson NK cells or agonists of activating receptors on NK cells. Forexample, agonist anti-huICOS antibodies can be combined with antagonistsof KIR (e.g., lirilumab).

Yet other agents for combination therapies include agents that inhibitor deplete macrophages or monocytes, including but not limited to CSF-1Rantagonists such as CSF-1R antagonist antibodies including RG7155 (WO11/70024, WO 11/107553, WO 11/131407, WO 13/87699, WO 13/119716, WO13/132044) or FPA-008 (WO 11/140249; WO 13/169264; WO 14/036357).

In some embodiments, agonist anti-huICOS antibodies described herein areused together with one or more of agonistic agents that ligate positiveco-stimulatory receptors, blocking agents that attenuate signalingthrough inhibitory receptors, and one or more agents that increasesystemically the frequency of anti-tumor T cells, agents that overcomedistinct immune suppressive pathways within the tumor microenvironment(e.g., block inhibitory receptor engagement (e.g., PD-L1/PD-1interactions), deplete or inhibit Tregs (e.g., using an anti-CD25monoclonal antibody (e.g., daclizumab) or by ex vivo anti-CD25 beaddepletion), inhibit metabolic enzymes such as IDO, or reverse/prevent Tcell anergy or exhaustion) and agents that trigger innate immuneactivation and/or inflammation at tumor sites.

Provided herein are methods for stimulating an immune response in asubject comprising administering to the subject a ICOS agonist, e.g., anantibody, and one or more additional immunostimulatory antibodies, suchas a PD-1 antagonist, e.g., antagonist antibody, a PD-L1 antagonist,e.g., antagonist antibody, a CTLA-4 antagonist, e.g., antagonistantibody and/or a LAG3 antagonist, e.g., an antagonist antibody, suchthat an immune response is stimulated in the subject, for example toinhibit tumor growth or to stimulate an anti-viral response. In oneembodiment, the subject is administered an agonist anti-huICOS antibodyand an antagonist anti-PD-1 antibody. In one embodiment, the subject isadministered an agonist anti-huICOS antibody and an antagonistanti-PD-L1 antibody. In one embodiment, the subject is administered anagonist anti-huICOS antibody and an antagonist anti-CTLA-4 antibody. Inone embodiment, the at least one additional immunostimulatory antibody(e.g., an antagonist anti-PD-1, an antagonist anti-PD-L1, an antagonistanti-CTLA-4 and/or an antagonist anti-LAG3 antibody) is a humanantibody. Alternatively, the at least one additional immunostimulatoryantibody can be, for example, a chimeric or humanized antibody (e.g.,prepared from a mouse or hamster anti-PD-1, anti-PD-L1, anti-CTLA-4and/or anti-LAG3 antibody).

Provided herein are methods for treating a hyperproliferative disease(e.g., cancer), comprising administering an agonist anti-huICOS antibodyand an antagonist PD-1 antibody to a subject. In some embodiments thecancer is non-small cell lung cancer (NSCLC) or colorectal cancer (CRC).In some embodiments the cancer is characterized by tumors with (i)elevated expression of CD32A/CD32B (FcγRIIa/Fcγ), and/or (ii-a) elevatedexpression of ICOS or (ii-b) reduced expression of ICOS-L, for exampleas detected by flow cytometry or immunohistochemistry (IHC). Tumor typeswith moderate to high ICOS RNA expression include head and neck, lung,cervical, kidney, pancreatic, breast and colorectal cancers, suggestingthat these cancers might also exhibit elevated ICOS protein expression.In certain embodiments, the agonist is administered at a subtherapeuticdose, the anti-PD-1 antibody is administered at a subtherapeutic dose,or both are administered at a subtherapeutic dose. Also provided hereinare methods for altering an adverse event associated with treatment of ahyperproliferative disease with an immunostimulatory agent. In oneembodiment, the method comprises administering an agonist anti-huICOSantibody and a subtherapeutic dose of anti-PD-1 antibody to a subject.In some embodiments, the subject is a human. In some embodiments, theanti-PD-1 antibody is a human monoclonal antibody and the agonistanti-huICOS antibody is a humanized monoclonal antibody, such as anantibody comprising the CDRs or variable regions of the antibodiesdisclosed herein.

Anti-PD-1 antibodies that are known in the art can be used in thepresently described methods. Various human monoclonal antibodies thatbind specifically to PD-1 with high affinity have been disclosed in U.S.Pat. No. 8,008,449. Anti-PD-1 human antibodies disclosed in U.S. Pat.No. 8,008,449 have been demonstrated to exhibit one or more of thefollowing characteristics: (a) bind to human PD-1 with a K_(D) of 1×10⁻⁷M or less, as determined by surface plasmon resonance using a Biacorebiosensor system; (b) do not substantially bind to human CD28, CTLA-4 orICOS; (c) increase T-cell proliferation in a Mixed Lymphocyte Reaction(MLR) assay; (d) increase interferon-γ production in an MLR assay; (e)increase IL-2 secretion in an MLR assay; (f) bind to human PD-1 andcynomolgus monkey PD-1; (g) inhibit the binding of PD-L1 and/or PD-L2 toPD-1; (h) stimulate antigen-specific memory responses; (i) stimulateantibody responses; and (j) inhibit tumor cell growth in vivo. Anti-PD-1antibodies usable in the present invention include monoclonal antibodiesthat bind specifically to human PD-1 and exhibit at least one, in someembodiments, at least five, of the preceding characteristics.

Other anti-PD-1 monoclonal antibodies have been described in, forexample, U.S. Pat. Nos. 6,808,710, 7,488,802, 8,168,757 and 8,354,509,US Publication No. 2016/0272708, and PCT Publication Nos. WO2012/145493, WO 2008/156712, WO 2015/112900, WO 2012/145493, WO2015/112800, WO 2014/206107, WO 2015/35606, WO 2015/085847, WO2014/179664, WO 2017/020291, WO 2017/020858, WO 2016/197367, WO2017/024515, WO 2017/025051, WO 2017/123557, WO 2016/106159, WO2014/194302, WO 2017/040790, WO 2017/133540, WO 2017/132827, WO2017/024465, WO 2017/025016, WO 2017/106061, WO 2017/19846, WO2017/024465, WO 2017/025016, WO 2017/132825, and WO 2017/133540 each ofwhich is incorporated by reference in its entirety.

In some embodiments, the anti-PD-1 antibody is nivolumab (also known asOPDIVO®, 5C4, BMS-936558, MDX-1106, and ONO-4538), pembrolizumab (Merck;also known as KEYTRUDA®, lambrolizumab, and MK-3475; see WO2008/156712),PDR001 (Novartis; see WO 2015/112900), MEDI-0680 (AstraZeneca; alsoknown as AMP-514; see WO 2012/145493), cemiplimab (Regeneron; also knownas REGN-2810; see WO 2015/112800), JS001 (TAIZHOU JUNSHI PHARMA; seeSi-Yang Liu et al., J. Hematol. Oncol. 10:136 (2017)), BGB-A317(Beigene; see WO 2015/35606 and US 2015/0079109), INCSHR1210 (JiangsuHengrui Medicine; also known as SHR-1210; see WO 2015/085847; Si-YangLiu et al., J. Hematol. Oncol. 10:136 (2017)), TSR-042 (TesaroBiopharmaceutical; also known as ANB011; see WO2014/179664), GLS-010(Wuxi/Harbin Gloria Pharmaceuticals; also known as WBP3055; see Si-YangLiu et al., J Hematol. Oncol. 10:136 (2017)), AM-0001 (Armo), STI-1110(Sorrento Therapeutics; see WO 2014/194302), AGEN2034 (Agenus; see WO2017/040790), MGA012 (Macrogenics, see WO 2017/19846), or IBI308(Innovent; see WO 2017/024465, WO 2017/025016, WO 2017/132825, and WO2017/133540).

In one embodiment, the anti-PD-1 antibody is nivolumab. Nivolumab is afully human IgG4 (S228P) PD-1 immune checkpoint inhibitor antibody thatselectively prevents interaction with PD-1 ligands (PD-L1 and PD-L2),thereby blocking the down-regulation of antitumor T-cell functions (U.S.Pat. No. 8,008,449; Wang et al., 2014 Cancer Immunol Res. 2(9):846-56).

In another embodiment, the anti-PD-1 antibody is pembrolizumab.Pembrolizumab is a humanized monoclonal IgG4 (S228P) antibody directedagainst human cell surface receptor PD-1 (programmed death-1 orprogrammed cell death-1). Pembrolizumab is described, for example, inU.S. Pat. Nos. 8,354,509 and 8,900,587.

Anti-PD-1 antibodies usable in the disclosed methods also includeisolated antibodies that bind specifically to human PD-1 andcross-compete for binding to human PD-1 with any anti-PD-1 antibodydisclosed herein, e.g., nivolumab (see, e.g., U.S. Pat. Nos. 8,008,449and 8,779,105; WO 2013/173223). In some embodiments, the anti-PD-1antibody binds the same epitope as any of the anti-PD-1 antibodiesdescribed herein, e.g., nivolumab. The ability of antibodies tocross-compete for binding to an antigen indicates that these monoclonalantibodies bind to the same epitope region of the antigen and stericallyhinder the binding of other cross-competing antibodies to thatparticular epitope region. These cross-competing antibodies are expectedto have functional properties very similar those of the referenceantibody, e.g., nivolumab, by virtue of their binding to the sameepitope region of PD-1. Cross-competing antibodies can be readilyidentified based on their ability to cross-compete with nivolumab instandard PD-1 binding assays such as Biacore analysis, ELISA assays orflow cytometry (see, e.g., WO 2013/173223).

In certain embodiments, the antibodies that cross-compete for binding tohuman PD-1 with, or bind to the same epitope region of human PD-1antibody, nivolumab, are monoclonal antibodies. For administration tohuman subjects, these cross-competing antibodies are chimericantibodies, engineered antibodies, or humanized or human antibodies.Such chimeric, engineered, humanized or human monoclonal antibodies canbe prepared and isolated by methods well known in the art.

Anti-PD-1 antibodies usable in the methods of the disclosed inventionalso include antigen-binding portions of the above antibodies. It hasbeen amply demonstrated that the antigen-binding function of an antibodycan be performed by fragments of a full-length antibody.

Anti-PD-1 antibodies suitable for use in the disclosed methods orcompositions are antibodies that bind to PD-1 with high specificity andaffinity, block the binding of PD-L1 and or PD-L2, and inhibit theimmunosuppressive effect of the PD-1 signaling pathway. In any of thecompositions or methods disclosed herein, an anti-PD-1 “antibody”includes an antigen-binding portion or fragment that binds to the PD-1receptor and exhibits the functional properties similar to those ofwhole antibodies in inhibiting ligand binding and up-regulating theimmune system. In certain embodiments, the anti-PD-1 antibody orantigen-binding portion thereof cross-competes with nivolumab forbinding to human PD-1.

Provided herein are methods for treating a hyperproliferative disease(e.g., cancer), comprising administering an agonist anti-huICOS antibodyand an antagonist PD-L1 antibody to a subject. In certain embodiments,the agonist anti-huICOS antibody is administered at a subtherapeuticdose, the anti-PD-L1 antibody is administered at a subtherapeutic dose,or both are administered at a subtherapeutic dose. Provided herein aremethods for altering an adverse event associated with treatment of ahyperproliferative disease with an immunostimulatory agent, comprisingadministering an agonist anti-huICOS antibody and a subtherapeutic doseof anti-PD-L1 antibody to a subject. In certain embodiments, the subjectis human. In certain embodiments, the anti-PD-L1 antibody is a humansequence monoclonal antibody and the agonist anti-huICOS antibody is ahumanized monoclonal antibody, such as an antibody comprising the CDRsor variable regions of the antibodies disclosed herein.

Anti-PD-L1 antibodies that are known in the art can be used in themethods of the present disclosure. Examples of anti-PD-L1 antibodiesuseful in the methods of the present disclosure include the antibodiesdisclosed in U.S. Pat. No. 9,580,507. Anti-PD-L1 human monoclonalantibodies disclosed in U.S. Pat. No. 9,580,507 have been demonstratedto exhibit one or more of the following characteristics: (a) bind tohuman PD-L1 with a K_(D) of 1×10-7 M or less, as determined by SPR usinga Biacore biosensor system; (b) increase T-cell proliferation in a MixedLymphocyte Reaction (MLR) assay; (c) increase interferon-V production inan MLR assay; (d) increase IL-2 secretion in an MLR assay; (e) stimulateantibody responses; and (f) reverse the effect of T regulatory cells onT cell effector cells and/or dendritic cells. Anti-PD-L1 antibodiesusable in the present invention include monoclonal antibodies that bindspecifically to human PD-L1 and exhibit at least one, in someembodiments, at least five, of the preceding characteristics.

In certain embodiments, the anti-PD-L1 antibody is BMS-936559 (alsoknown as 12A4, MDX-1105; see, e.g., U.S. Pat. No. 7,943,743 and WO2013/173223), atezolizumab (Roche; also known as TECENTRIQ®; MPDL3280A,RG7446; see U.S. Pat. No. 8,217,149; see, also, Herbst et al. (2013) JClin Oncol 31(suppl):3000), durvalumab (AstraZeneca; also known asIMFINZI™, MEDI-4736; see WO 2011/066389), avelumab (Pfizer; also knownas BAVENCIO®, MSB-0010718C; see WO 2013/079174), STI-1014 (Sorrento; seeWO2013/181634), CX-072 (Cytomx; see WO2016/149201), KN035 (3DMed/Alphamab; see Zhang et al., Cell Discov. 7:3 (March 2017), LY3300054(Eli Lilly Co.; see, e.g., WO 2017/034916), or CK-301 (CheckpointTherapeutics; see Gorelik et al., AACR:Abstract 4606 (April 2016)).

In certain embodiments, the PD-L1 antibody is atezolizumab (TECENTRIQ®).Atezolizumab is a fully humanized IgG1 monoclonal anti-PD-L1 antibody.

In certain embodiments, the PD-L1 antibody is durvalumab (IMFINZI™).Durvalumab is a human IgG1 kappa monoclonal anti-PD-L1 antibody.

In certain embodiments, the PD-L1 antibody is avelumab (BAVENCIO®).Avelumab is a human IgG1 lambda monoclonal anti-PD-L1 antibody.

In other embodiments, the anti-PD-L1 monoclonal antibody is 28-8, 28-1,28-12, 29-8, 5H1, or any combination thereof.

Anti-PD-L1 antibodies usable in the disclosed methods also includeisolated antibodies that bind specifically to human PD-L1 andcross-compete for binding to human PD-L1 with any anti-PD-L1 antibodydisclosed herein, e.g., atezolizumab, durvalumab, and/or avelumab. Insome embodiments, the anti-PD-L1 antibody binds the same epitope as anyof the anti-PD-L1 antibodies described herein, e.g., atezolizumab,durvalumab, and/or avelumab. The ability of antibodies to cross-competefor binding to an antigen indicates that these antibodies bind to thesame epitope region of the antigen and sterically hinder the binding ofother cross-competing antibodies to that particular epitope region.These cross-competing antibodies are expected to have functionalproperties very similar those of the reference antibody, e.g.,atezolizumab and/or avelumab, by virtue of their binding to the sameepitope region of PD-L1. Cross-competing antibodies can be readilyidentified based on their ability to cross-compete with atezolizumaband/or avelumab in standard PD-L1 binding assays such as Biacoreanalysis, ELISA assays or flow cytometry (see, e.g., WO 2013/173223).

In certain embodiments, the antibodies that cross-compete for binding tohuman PD-L1 with, or bind to the same epitope region of human PD-L1antibody as, atezolizumab, durvalumab, and/or avelumab, are monoclonalantibodies. For administration to human subjects, these cross-competingantibodies are chimeric antibodies, engineered antibodies, or humanizedor human antibodies. Such chimeric, engineered, humanized or humanmonoclonal antibodies can be prepared and isolated by methods well knownin the art.

Anti-PD-L1 antibodies usable in the methods of the disclosed inventionalso include antigen-binding portions of the above antibodies. It hasbeen amply demonstrated that the antigen-binding function of an antibodycan be performed by fragments of a full-length antibody.

Anti-PD-L1 antibodies suitable for use in the disclosed methods orcompositions are antibodies that bind to PD-L1 with high specificity andaffinity, block the binding of PD-1, and inhibit the immunosuppressiveeffect of the PD-1 signaling pathway. In any of the compositions ormethods disclosed herein, an anti-PD-L1 “antibody” includes anantigen-binding portion or fragment that binds to PD-L1 and exhibits thefunctional properties similar to those of whole antibodies in inhibitingreceptor binding and up-regulating the immune system. In certainembodiments, the anti-PD-L1 antibody or antigen-binding portion thereofcross-competes with atezolizumab, durvalumab, and/or avelumab forbinding to human PD-L1.

In one embodiment, the agonist anti-huICOS antibody of the presentinvention is combined with an antagonist of PD-1/PD-L1 signaling, suchas a PD-1 antagonist (e.g., nivolumab, also known as MDX1106, asdescribed in WO 06/121168) or a PD-L1 antagonist, in combination with athird immunotherapeutic agent (e.g., an anti-ICOS antibody, such asICOS.33 IgG1f S267E, combined with nivolumab and ipilimumab). In oneembodiment the third immunotherapeutic agent is a CTLA-4 antagonistantibody. In certain embodiments, the anti-CTLA-4 antibody is YERVOY®(ipilimumab or antibody 10D1, described in PCT Publication WO 01/14424)or tremelimumab (formerly ticilimumab, CP-675,206). In one embodimentthe third immunotherapeutic agent is a GITR antagonist or an OX-40antagonist, such as the anti-GITR or anti-OX40 antibodies disclosedherein. In one embodiment, the third immunotherapeutic agent is a GITRagonist, such as an agonistic GITR antibody. Suitable GITR antibodiesinclude, for example, BMS-986153, BMS-986156, TRX-518 (WO06/105021,WO09/009116) and MK-4166 (WO11/028683). In one embodiment, the thirdimmunotherapeutic agent is an IDO antagonist. Suitable IDO antagonistsinclude, for example, INCB-024360 (WO2006/122150, WO07/75598,WO08/36653, WO08/36642), indoximod, or NLG-919 (WO09/73620,WO09/1156652, WO11/56652, WO12/142237).

Provided herein are methods for treating a hyperproliferative disease(e.g., cancer), comprising administering an agonist anti-huICOS antibodydescribed herein and a CTLA-4 antagonist antibody to a subject. Incertain embodiments, the agonist anti-huICOS antibody is administered ata subtherapeutic dose, the anti-CTLA-4 antibody is administered at asubtherapeutic dose, or both are administered at a subtherapeutic dose.Provided herein are methods for altering an adverse event associatedwith treatment of a hyperproliferative disease with an immunostimulatoryagent, comprising administering an agonist anti-huICOS antibody and asubtherapeutic dose of anti-CTLA-4 antibody to a subject. In certainembodiments, the subject is human.

Anti-CTLA-4 antibodies that are known in the art can be used in themethods of the present disclosure. Anti-CTLA-4 antibodies of the instantinvention bind to human CTLA-4 so as to disrupt the interaction ofCTLA-4 with a human B7 receptor. Because the interaction of CTLA-4 withB7 transduces a signal leading to inactivation of T-cells bearing theCTLA-4 receptor, disruption of the interaction effectively induces,enhances or prolongs the activation of such T cells, thereby inducing,enhancing or prolonging an immune response.

Human monoclonal antibodies that bind specifically to CTLA-4 with highaffinity have been disclosed in U.S. Pat. No. 6,984,720. Otheranti-CTLA-4 monoclonal antibodies have been described in, for example,U.S. Pat. Nos. 5,977,318, 6,051,227, 6,682,736, and 7,034,121 andInternational Publication Nos. WO 2012/122444, WO 2007/113648, WO2016/196237, and WO 2000/037504, each of which is incorporated byreference herein in its entirety. The anti-CTLA-4 human monoclonalantibodies disclosed in U.S. Pat. No. 6,984,720 have been demonstratedto exhibit one or more of the following characteristics: (a) bindsspecifically to human CTLA-4 with a binding affinity reflected by anequilibrium association constant (K_(a)) of at least about 10⁷ M⁻¹, orabout 10⁹ M⁻¹, or about 10¹⁰ M⁻¹ to 10¹¹ M⁻¹ or higher, as determined byBiacore analysis; (b) a kinetic association constant (k_(a)) of at leastabout 10³, about 10⁴, or about 10⁵ m⁻¹ s⁻¹; (c) a kinetic disassociationconstant (k_(d)) of at least about 10³, about 10⁴, or about 10⁵ m⁻¹ s⁻¹;and (d) inhibits the binding of CTLA-4 to B7-1 (CD80) and B7-2 (CD86).Anti-CTLA-4 antibodies useful for the present invention includemonoclonal antibodies that bind specifically to human CTLA-4 and exhibitat least one, at least two, or at least three of the precedingcharacteristics.

In certain embodiments, the CTLA-4 antibody is ipilimumab (also known asYERVOY®, MDX-010, 10D1; see U.S. Pat. No. 6,984,720), MK-1308 (Merck),AGEN-1884 (Agenus Inc.; see WO 2016/196237), or tremelimumab(AstraZeneca; also known as ticilimumab, CP-675,206; see WO 2000/037504and Ribas, Update Cancer Ther. 2(3): 133-39 (2007)). In particularembodiments, the anti-CTLA-4 antibody is ipilimumab.

In particular embodiments, the CTLA-4 antibody is ipilimumab for use inthe methods disclosed herein. Ipilimumab is a fully human, IgG1monoclonal antibody that blocks the binding of CTLA-4 to its B7 ligands,thereby stimulating T cell activation and improving overall survival(OS) in patients with advanced melanoma.

In particular embodiments, the CTLA-4 antibody is tremelimumab.

In particular embodiments, the CTLA-4 antibody is MK-1308.

In particular embodiments, the CTLA-4 antibody is AGEN-1884.

Anti-CTLA-4 antibodies usable in the disclosed methods also includeisolated antibodies that bind specifically to human CTLA-4 andcross-compete for binding to human CTLA-4 with any anti-CTLA-4 antibodydisclosed herein, e.g., ipilimumab and/or tremelimumab. In someembodiments, the anti-CTLA-4 antibody binds the same epitope as any ofthe anti-CTLA-4 antibodies described herein, e.g., ipilimumab and/ortremelimumab. The ability of antibodies to cross-compete for binding toan antigen indicates that these antibodies bind to the same epitoperegion of the antigen and sterically hinder the binding of othercross-competing antibodies to that particular epitope region. Thesecross-competing antibodies are expected to have functional propertiesvery similar those of the reference antibody, e.g., ipilimumab and/ortremelimumab, by virtue of their binding to the same epitope region ofCTLA-4. Cross-competing antibodies can be readily identified based ontheir ability to cross-compete with ipilimumab and/or tremelimumab instandard CTLA-4 binding assays such as Biacore analysis, ELISA assays orflow cytometry (see, e.g., WO 2013/173223).

In certain embodiments, the antibodies that cross-compete for binding tohuman CTLA-4 with, or bind to the same epitope region of human CTLA-4antibody as, ipilimumab and/or tremelimumab, are monoclonal antibodies.For administration to human subjects, these cross-competing antibodiesare chimeric antibodies, engineered antibodies, or humanized or humanantibodies. Such chimeric, engineered, humanized or human monoclonalantibodies can be prepared and isolated by methods well known in theart.

Anti-CTLA-4 antibodies usable in the methods of the disclosed inventionalso include antigen-binding portions of the above antibodies. It hasbeen amply demonstrated that the antigen-binding function of an antibodycan be performed by fragments of a full-length antibody.

Anti-CTLA-4 antibodies suitable for use in the disclosed methods orcompositions are antibodies that bind to CTLA-4 with high specificityand affinity, block the activity of CTLA-4, and disrupt the interactionof CTLA-4 with a human B7 receptor. In any of the compositions ormethods disclosed herein, an anti-CTLA-4 “antibody” includes anantigen-binding portion or fragment that binds to CTLA-4 and exhibitsthe functional properties similar to those of whole antibodies ininhibiting the interaction of CTLA-4 with a human B7 receptor andup-regulating the immune system. In certain embodiments, the anti-CTLA-4antibody or antigen-binding portion thereof cross-competes withipilimumab and/or tremelimumab for binding to human CTLA-4.

In one embodiment, the agonist anti-huICOS antibody of the presentinvention is combined with an anti-CTLA-4 antibody, in combination witha third immunotherapeutic agent. In one embodiment the thirdimmunotherapeutic agent is a GITR antagonist or an OX-40 antagonist,such as the anti-GITR or anti-OX40 antibodies disclosed herein. In oneembodiment, the third immunotherapeutic agent is a GITR agonist, such asan agonistic GITR antibody. Suitable GITR antibodies include, forexample, BMS-986153, BMS-986156, TRX-518 (WO06/105021, WO09/009116) andMK-4166 (WO11/028683). In one embodiment, the third immunotherapeuticagent is an IDO antagonist. Suitable IDO antagonists include, forexample, INCB-024360 (WO2006/122150, WO07/75598, WO08/36653,WO08/36642), indoximod, or NLG-919 (WO09/73620, WO09/1156652,WO11/56652, WO12/142237).

Provided herein are methods for treating a hyperproliferative disease(e.g., cancer), comprising administering an agonist anti-huICOS antibodyand an anti-LAG-3 antibody to a subject. In further embodiments, theagonist anti-huICOS antibody is administered at a subtherapeutic dose,the anti-LAG-3 antibody is administered at a subtherapeutic dose, orboth are administered at a subtherapeutic dose. Provided herein aremethods for altering an adverse event associated with treatment of ahyperproliferative disease with an immunostimulatory agent, comprisingadministering an agonist anti-huICOS antibody and a subtherapeutic doseof anti-LAG-3 antibody to a subject. In certain embodiments, the subjectis human. In certain embodiments, the anti-LAG-3 antibody is a humansequence monoclonal antibody and the agonist anti-huICOS antibody is ahumanized monoclonal antibody, such as an antibody comprising the CDRsor variable regions of the antibodies disclosed herein. Examples ofanti-LAG3 antibodies include antibodies comprising the CDRs or variableregions of antibodies 25F7, 26H10, 25E3, 8B7, 11F2 or 17E5, which aredescribed in U.S. Patent Publication No. US2011/0150892 andWO2014/008218. In one embodiment, an anti-LAG-3 antibody is BMS-986016.Other anti-LAG-3 antibodies that can be used include IMP731 described inUS 2011/007023 or IMP-321. Anti-LAG-3 antibodies that compete withand/or bind to the same epitope as that of any of these antibodies mayalso be used in combination treatments.

In certain embodiments, the anti-LAG-3 antibody binds to human LAG-3with a K_(D) of 5×10⁻⁸ M or less, binds to human LAG-3 with a K_(D) of1×10⁻⁸ M or less, binds to human LAG-3 with a K_(D) of 5×10⁻⁹ M or less,or binds to human LAG-3 with a K_(D) of between 1×10⁻⁸ M and 1×10⁻¹⁰ Mor less.

Administration of agonist anti-huICOS antibodies described herein andantagonists, e.g., antagonist antibodies, to one or more second targetantigens such as LAG-3 and/or CTLA-4 and/or PD-1 and/or PD-L1 canenhance the immune response to cancerous cells in the patient. Cancerswhose growth may be inhibited using the antibodies of the instantdisclosure include cancers typically responsive to immunotherapy.Examples of cancers for treatment with the combination therapy describedherein include, but are not limited to, the described above in thediscussion of monotherapy with agonist anti-huICOS antibodies.

In certain embodiments, the combination of therapeutic antibodiesdiscussed herein can be administered concurrently as a singlecomposition in a pharmaceutically acceptable carrier, or concurrently asseparate compositions with each antibody in a pharmaceuticallyacceptable carrier. In another embodiment, the combination oftherapeutic antibodies can be administered sequentially. For example, ananti-CTLA-4 antibody and an agonist anti-huICOS antibody can beadministered sequentially, such as anti-CTLA-4 antibody beingadministered first and agonist anti-huICOS antibody second, or agonistanti-huICOS antibody being administered first and anti-CTLA-4 antibodysecond. Additionally or alternatively, an anti-PD-1 antibody and anagonist anti-huICOS antibody can be administered sequentially, such asanti-PD-1 antibody being administered first and agonist anti-huICOSantibody second, or agonist anti-huICOS antibody being administeredfirst and anti-PD-1 antibody second. Additionally or alternatively, ananti-PD-L1 antibody and an agonist anti-huICOS antibody can beadministered sequentially, such as anti-PD-L1 antibody beingadministered first and agonist anti-huICOS antibody second, or agonistanti-huICOS antibody being administered first and anti-PD-L1 antibodysecond. Additionally or alternatively, an anti-LAG-3 antibody and anagonist anti-huICOS antibody can be administered sequentially, such asanti-LAG-3 antibody being administered first and agonist anti-huICOSantibody second, or agonist anti-huICOS antibody being administeredfirst and anti-LAG-3 antibody second.

Furthermore, if more than one dose of the combination therapy isadministered sequentially, the order of the sequential administrationcan be reversed or kept in the same order at each time point ofadministration, sequential administrations can be combined withconcurrent administrations, or any combination thereof. For example, thefirst administration of a combination anti-CTLA-4 antibody and agonistanti-huICOS antibody can be concurrent, the second administration can besequential with anti-CTLA-4 antibody first and agonist anti-huICOSantibody second, and the third administration can be sequential withagonist anti-huICOS antibody first and anti-CTLA-4 antibody second, etc.Additionally or alternatively, the first administration of a combinationanti-PD-1 antibody and agonist anti-huICOS antibody can be concurrent,the second administration can be sequential with anti-PD-1 antibodyfirst and agonist anti-huICOS antibody second, and the thirdadministration can be sequential with agonist anti-huICOS antibody firstand anti-PD-1 antibody second, etc. Additionally or alternatively, thefirst administration of a combination anti-PD-L1 antibody and agonistanti-huICOS antibody can be concurrent, the second administration can besequential with anti-PD-L1 antibody first and agonist anti-huICOSantibody second, and the third administration can be sequential withagonist anti-huICOS antibody first and anti-PD-L1 antibody second, etc.Additionally or alternatively, the first administration of a combinationanti-LAG-3 antibody and agonist anti-huICOS antibody can be concurrent,the second administration can be sequential with anti-LAG-3 antibodyfirst and agonist anti-huICOS antibody second, and the thirdadministration can be sequential with agonist anti-huICOS antibody firstand anti-LAG-3 antibody second, etc. Another representative dosingscheme can involve a first administration that is sequential withagonist anti-huICOS first and anti-CTLA-4 antibody (and/or anti-PD-1antibody and/or anti-PD-L1 antibody and/or anti-LAG-3 antibody) second,and subsequent administrations may be concurrent.

In one embodiment, an agonist anti-huICOS antibody, as soleimmunotherapeutic agent, or the combination of an agonist anti-huICOSantibody and one or more additional immunotherapeutic antibodies (e.g.,anti-CTLA-4 and/or anti-PD-1 and/or anti-PD-L1 and/or anti-LAG-3antibody) may be further combined with an immunogenic agent, such ascancerous cells, purified tumor antigens (including recombinantproteins, peptides, and carbohydrate molecules), cells, and cellstransfected with genes encoding immune stimulating cytokines (He et al.(2004) J. Immunol. 173:4919-28). Non-limiting examples of tumor vaccinesthat can be used include peptides of melanoma antigens, such as peptidesof gp 100, MAGE antigens, Trp-2, MART 1 and/or tyrosinase, or tumorcells transfected to express the cytokine GM-CSF (discussed furtherbelow). An ICOS agonist and one or more additional antibodies (e.g.,CTLA-4 and/or PD-1 and/or PD-L1 and/or LAG-3 blockade) can also befurther combined with standard cancer treatments. For example, an ICOSagonist and one or more additional antibodies (e.g., CTLA-4 and/or PD-1and/or PD-L1 and/or LAG-3 blockade) may be combined withchemotherapeutic regimes. In one embodiment, an anti-huICOS agonistantibody is administered to a patient with an anti-CTLA-4 antibodyand/or anti-PD-1 antibody and/or anti-PD-L1 antibody and/or anti-LAG-3antibody in combination with decarbazine for the treatment of melanoma.In one embodiment, an anti-huICOS agonist antibody is administered to apatient with an anti-CTLA-4 antibody and/or anti-PD-1 antibody and/oranti-PD-L1 antibody and/or anti-LAG-3 antibody in combination withinterleukin-2 (IL-2) for the treatment of cancer, including melanoma.Without wishing to be bound to theory, combined use of ICOS agonism andCTLA-4 and/or PD-1 and/or PD-L1 and/or LAG-3 antagonism withchemotherapy may function synergistically as the cytotoxic action ofmost chemotherapeutic compounds may result in increased levels of tumorantigen in the antigen presentation pathway. Other combination therapiesthat may result in synergy with a combined ICOS agonism with or withoutand CTLA-4 and/or PD-1 and/or PD-L1 and/or LAG-3 antagonism throughcytotoxicity include radiation, surgery, or hormone deprivation. Inanother embodiment, angiogenesis inhibitors may be combined with ananti-huICOS antibody and CTLA-4 and/or PD-1 and/or PD-L1 and/or LAG-3antagonism.

In one embodiment, an anti-huICOS antibody as sole immunotherapeuticagent, or a combination of an anti-huICOS antibody and CTLA-4 and/orPD-1 and/or PD-L1 and/or LAG-3 blocking antibodies can also be used incombination with bispecific antibodies that target Fcα or Fcγreceptor-expressing effector cells to tumor cells. See, e.g., U.S. Pat.Nos. 5,922,845 and 5,837,243. Bispecific antibodies can be used totarget two separate antigens. The T cell arm of these responses would beaugmented by the use of a combined ICOS agonism and CTLA-4 and/or PD-1and/or PD-L1 and/or LAG-3 blockade.

In one embodiment an anti-ICOS antibody as sole immunotherapeutic agentor a combination of an anti-ICOS antibody and additionalimmunostimulating agent, e.g., anti-CTLA-4 antibody and/or anti-PD-1antibody and/or anti-PD-L1 antibody and/or anti-LAG-3 antibody, can beused in conjunction with an anti-neoplastic agent, such as RITUXAN®(rituximab), HERCEPTIN® (trastuzumab), BEXXAR® (tositumomab), ZEVALIN®(ibritumomab), CAMPATH® (alemtuzumab), LYMPHOCIDE® (eprtuzumab),AVASTIN® (bevacizumab), and TARCEVA® (erlotinib). By way of example andnot wishing to be bound by theory, treatment with an anti-cancerantibody or an anti-cancer antibody conjugated to a toxin can lead tocancer cell death (e.g., tumor cells) which may potentiate an immuneresponse mediated by the immunostimulating agent, e.g., anti-ICOSantibody, anti-TIGIT antibody, anti-CTLA-4 antibody, anti-PD-1 antibody,anti-PD-L1 antibody or anti-LAG-3 antibody. In one embodiment, atreatment of a hyperproliferative disease (e.g., a cancer tumor) caninclude an anti-cancer agent, e.g., antibody, in combination with anagonist anti-huICOS antibody and optionally an additionalimmunostimulating agent, e.g., anti-CTLA-4 antibody and/or anti-PD-1antibody and/or anti-PD-L1 antibody and/or anti-LAG-3 antibody,concurrently or sequentially or any combination thereof, which canpotentiate an anti-tumor immune responses by the host.

Provided herein are methods for reducing, ameliorating or abrogating anadverse event associated with treatment of a hyperproliferative disease(e.g., cancer) with an immunostimulatory agent, comprising administeringan agonist anti-huICOS antibody with or without an anti-CTLA-4 and/oranti-PD-1 and/or anti-PD-L1 and/or anti-LAG-3 antibody, to a subject. Inone embodiment, the method reduces the incidence of immunostimulatorytherapeutic antibody-induced colitis or diarrhea by administering anon-absorbable steroid to the patient. As used herein, a “non-absorbablesteroid” is a glucocorticoid that exhibits extensive first passmetabolism such that, following metabolism in the liver, thebioavailability of the steroid is low, i.e., less than about 20%. In oneembodiment described herein, the non-absorbable steroid is budesonide.Budesonide is a locally-acting glucocorticosteroid, which is extensivelymetabolized, primarily by the liver, following oral administration.ENTOCORT EC® (Astra-Zeneca) is a pH- and time-dependent oral formulationof budesonide developed to optimize drug delivery to the ileum andthroughout the colon. ENTOCORT EC® is approved in the U.S. for thetreatment of mild to moderate Crohn's disease involving the ileum and/orascending colon. The usual oral dosage of ENTOCORT EC® for the treatmentof Crohn's disease is 6 to 9 mg/day. ENTOCORT EC® is released in theintestines before being absorbed and retained in the gut mucosa. Once itpasses through the gut mucosa target tissue, ENTOCORT EC® is extensivelymetabolized by the cytochrome P450 system in the liver to metaboliteswith negligible glucocorticoid activity. Therefore, the bioavailabilityis low (about 10%). The low bioavailability of budesonide results in animproved therapeutic ratio compared to other glucocorticoids with lessextensive first-pass metabolism. Budesonide results in fewer adverseeffects, including less hypothalamic-pituitary suppression, thansystemically-acting corticosteroids. However, chronic administration ofENTOCORT EC® can result in systemic glucocorticoid effects such ashypercorticism and adrenal suppression. See PDR 58^(th) ed. 2004;608-610.

In one embodiment, an anti-ICOS antibody with or without CTLA-4 and/orPD-1 and/or PD-L1 and/or LAG-3 antagonist (i.e., immunostimulatorytherapeutic antibodies against ICOS and optionally anti-CTLA-4 and/oranti-PD-1 and/or anti-PD-L1 and/or anti-LAG-3 antibodies) in conjunctionwith a non-absorbable steroid can be further combined with a salicylate.Salicylates include 5-ASA agents such as, for example: sulfasalazine(AZULFIDINE®, Pharmacia & UpJohn); olsalazine (DIPENTUM®, Pharmacia &UpJohn); balsalazide (COLAZAL®, Salix Pharmaceuticals, Inc.); andmesalamine (ASACOL®, Procter & Gamble Pharmaceuticals; PENTASA®, ShireUS; CANASA®, Axcan Scandipharm, Inc.; ROWASA®, Solvay).

In accordance with the methods described herein, a salicylateadministered in combination with an anti-huICOS antibody with or withoutanti-CTLA-4 and/or anti-PD-1 and/or anti-PD-L1 and/or LAG-3 antibodiesand a non-absorbable steroid may include any overlapping or sequentialadministration of the salicylate and the non-absorbable steroid for thepurpose of decreasing the incidence of colitis induced by theimmunostimulatory antibodies. Thus, for example, methods for reducingthe incidence of colitis induced by the immunostimulatory antibodiesdescribed herein encompass administering a salicylate and anon-absorbable concurrently or sequentially (e.g., a salicylate isadministered 6 hours after a non-absorbable steroid), or any combinationthereof. Further, a salicylate and a non-absorbable steroid can beadministered by the same route (e.g., both are administered orally) orby different routes (e.g., a salicylate is administered orally and anon-absorbable steroid is administered rectally), which may differ fromthe route(s) used to administer the anti-huICOS and anti-CTLA-4 and/oranti-PD-1 and/or anti-PD-L1 and/or anti-LAG-3 antibodies.

The agonist anti-huICOS antibodies and combination antibody therapiesdescribed herein may also be used in conjunction with other well-knowntherapies that are selected for their particular usefulness against theindication being treated (e.g., cancer). Combinations of the agonistanti-huICOS antibodies described herein may be used sequentially withknown pharmaceutically acceptable agent(s).

In one embodiment, the agonist anti-huICOS antibodies and combinationantibody therapies described herein can be used in combination (e.g.,simultaneously or separately) with an additional treatment, such asirradiation, chemotherapy (e.g., using camptothecin (CPT-11),5-fluorouracil (5-FU), cisplatin, doxorubicin, irinotecan, paclitaxel,gemcitabine, cisplatin, paclitaxel, carboplatin-paclitaxel (Taxol),doxorubicin, 5-fu, or camptothecin+apo2l/TRAIL (a 6× combo)), one ormore proteasome inhibitors (e.g., bortezomib or MG132), one or moreBcl-2 inhibitors (e.g., BH3I-2′ (bcl-xl inhibitor), indoleaminedioxygenase-1 (IDO1) inhibitor (e.g., INCB24360), AT-101 (R-(−)-gossypolderivative), ABT-263 (small molecule), GX-15-070 (obatoclax), or MCL-1(myeloid leukemia cell differentiation protein-1) antagonists), iAP(inhibitor of apoptosis protein) antagonists (e.g., smac7, smac4, smallmolecule smac mimetic, synthetic smac peptides (see Fulda et al., NatMed 2002; 8:808-15), ISIS23722 (LY2181308), or AEG-35156 (GEM-640)),HDAC (histone deacetylase) inhibitors, anti-CD20 antibodies (e.g.,rituximab), angiogenesis inhibitors (e.g., bevacizumab), anti-angiogenicagents targeting VEGF and VEGFR (e.g., AVASTIN®), synthetictriterpenoids (see Hyer et al., Cancer Research 2005; 65:4799-808),c-FLIP (cellular FLICE-inhibitory protein) modulators (e.g., natural andsynthetic ligands of PPARγ (peroxisome proliferator-activated receptorγ), 5809354 or 5569100), kinase inhibitors (e.g., Sorafenib),trastuzumab, cetuximab, Temsirolimus, mTOR inhibitors such as rapamycinand temsirolimus, Bortezomib, JAK2 inhibitors, HSP90 inhibitors,PI3K-AKT inhibitors, Lenalildomide, GSK3β inhibitors, IAP inhibitorsand/or genotoxic drugs.

The agonist anti-huICOS antibodies and combination antibody therapiesdescribed herein can further be used in combination with one or moreanti-proliferative cytotoxic agents. Classes of compounds that may beused as anti-proliferative cytotoxic agents include, but are not limitedto, the following:

Alkylating agents (including, without limitation, nitrogen mustards,ethylenimine derivatives, alkyl sulfonates, nitrosoureas and triazenes):Uracil mustard, Chlormethine, Cyclophosphamide (CYTOXAN™) fosfamide,Melphalan, Chlorambucil, Pipobroman, Triethylenemelamine,Triethylenethiophosphoramine, Busulfan, Carmustine, Lomustine,Streptozocin, Dacarbazine, and Temozolomide.

Antimetabolites (including, without limitation, folic acid antagonists,pyrimidine analogs, purine analogs and adenosine deaminase inhibitors):Methotrexate, 5-Fluorouracil, Floxuridine, Cytarabine, 6-Mercaptopurine,6-Thioguanine, Fludarabine phosphate, Pentostatine, and Gemcitabine.

Suitable anti-proliferative agents for combining with agonistanti-huICOS antibodies, without limitation, taxanes, paclitaxel(paclitaxel is commercially available as TAXOL™), docetaxel,discodermolide (DDM), dictyostatin (DCT), Peloruside A, epothilones,epothilone A, epothilone B, epothilone C, epothilone D, epothilone E,epothilone F, furanoepothilone D, desoxyepothilone Bl,[17]-dehydrodesoxyepothilone B, [18]dehydrodesoxyepothilones B,C12,13-cyclopropyl-epothilone A, C6-C8 bridged epothilone A,trans-9,10-dehydroepothilone D, cis-9,10-dehydroepothilone D,16-desmethylepothilone B, epothilone B10, discoderomolide, patupilone(EPO-906), KOS-862, KOS-1584, ZK-EPO, ABJ-789, XAA296A (Discodermolide),TZT-1027 (soblidotin), ILX-651 (tasidotin hydrochloride), HalichondrinB, Eribulin mesylate (E-7389), Hemiasterlin (HTI-286), E-7974,Cyrptohycins, LY-355703, Maytansinoid immunoconjugates (DM-1), MKC-1,ABT-751, T1-38067, T-900607, SB-715992 (ispinesib), SB-743921, MK-0731,STA-5312, eleutherobin,17beta-acetoxy-2-ethoxy-6-oxo-B-homo-estra-1,3,5(10)-trien-3-ol,cyclostreptin, isolaulimalide, laulimalide,4-epi-7-dehydroxy-14,16-didemethyl-(+)-discodermolides, andcryptothilone 1, in addition to other microtubuline stabilizing agentsknown in the art.

In some embodiments it may be desirable to render aberrantlyproliferative cells quiescent in conjunction with or prior to treatmentwith agonist anti-huICOS antibodies described herein, e.g., byadministering to the patient hormones and steroids (including syntheticanalogs), such as 17a-Ethinylestradiol, Diethylstilbestrol,Testosterone, Prednisone, Fluoxymesterone, Dromostanolone propionate,Testolactone, Megestrolacetate, Methylprednisolone, Methyl-testosterone,Prednisolone, Triamcinolone, Chlorotrianisene, Hydroxyprogesterone,Aminoglutethimide, Estramustine, Medroxyprogesteroneacetate, Leuprolide,Flutamide, Toremifene, ZOLADEX™. When employing the methods orcompositions described herein, other agents used in the modulation oftumor growth or metastasis in a clinical setting, such as antimimetics,can also be administered as desired.

Methods for the safe and effective administration of chemotherapeuticagents are known to those skilled in the art. In addition, theiradministration is described in the standard literature. For example, theadministration of many of the chemotherapeutic agents is described inthe Physicians' Desk Reference (PDR), e.g., 1996 edition (MedicalEconomics Company, Montvale, N.J. 07645-1742, USA); the disclosure ofwhich is incorporated herein by reference thereto.

The chemotherapeutic agent(s) and/or radiation therapy can beadministered according to therapeutic protocols known in the art. Itwill be apparent to those skilled in the art that the administration ofthe chemotherapeutic agent(s) and/or radiation therapy can be varieddepending on the disease being treated and the known effects of thechemotherapeutic agent(s) and/or radiation therapy on that disease.Also, in accordance with the knowledge of the skilled clinician, thetherapeutic protocols (e.g., dosage amounts and times of administration)can be varied in view of the observed effects of the administeredtherapeutic agents on the patient, and in view of the observed responsesof the disease to the administered therapeutic agents.

Outcomes

Tumor response is determined, for example, by modified ResponseEvaluation Criteria in Solid Tumors (RECIST) established by the NCI.

With respect to target lesions, responses to therapy may include:

Complete Response (CR) Disappearance of all target lesions. Any (RECISTV1.1) pathological lymph nodes (whether target or non-target) must havereduction in short axis to <10 mm. Partial Response (PR) At least a 30%decrease in the sum of the (RECIST V1.1) diameters of target lesions,taking as reference the baseline sum diameters. Progressive Disease (PD)At least a 20% increase in the sum of the (RECIST V1.1) diameters oftarget lesions, taking as reference the smallest sum on study (thisincludes the baseline sum if that is the smallest on study). In additionto the relative increase of 20%, the sum must also demonstrate anabsolute increase of at least 5 mm. (Note: the appearance of one or morenew lesions is also considered progression). Stable Disease (SD) Neithersufficient shrinkage to qualify for (RECIST V1.1) PR nor sufficientincrease to qualify for PD, taking as reference the smallest sumdiameters while on study. Immune-related Disappearance of all targetlesions. Any Complete Response pathological lymph nodes (whether target(irCR) (irRECIST) or non-target) must have reduction in short axis to<10 mm. Immune-related Partial At least a 30% decrease in the sum ofResponse (irPR) diameters of target lesions and all new (irRECIST)measurable lesions (ie Percentage Change in Tumor Burden), taking asreference the baseline sum diameters. Note: the appearance of newmeasurable lesions is factored into the overall Tumor Burden, but doesnot automatically qualify as progressive disease until the sum of thediameters increases by ≥20% when compared to nadir. Immune-related Atleast a 20% increase in Tumor Burden Progressive Disease (ie the sum ofdiameters of target lesions, (irPD) (irRECIST) and any new measurablelesions) taking as reference the smallest sum on study (this includesthe baseline sum if that is the smallest on study). In addition to therelative increase of 20%, the sum must also demonstrate an absoluteincrease of at least 5 mm. Tumor assessments using immune- relatedcriteria for progressive disease incorporates the contribution of newmeasurable lesions. Each net percentage change in tumor burden perassessment accounts for the size and growth kinetics of both old and newlesions as they appear. Immune-related Stable Neither sufficientshrinkage to qualify for Disease (irSD) (irRECIST) irPR nor sufficientincrease to qualify for irPD, taking as reference the smallest sumdiameters while on study.

With respect to non-target lesions, responses to therapy may include:

Complete Response (CR) Disappearance of all non-target lesions. (RECISTV1.1) All lymph nodes must be non-pathological in size (<10 mm shortaxis). Non-CR/Non-PD Persistence of one or more non-target (RECIST V1.1)lesion(s). Progressive Disease (PD) Unequivocal progression of existingnon- (RECIST V1.1) target lesions. The appearance of one or more newlesions is also considered progression. Immune-related Disappearance ofall non-target lesions. All Complete Response lymph nodes must benon-pathological in (irCR) (irRECIST) size (<10 mm short axis).Immune-related Increases in number or size of non-target ProgressiveDisease (irPD) lesion(s) does not constitute progressive (irRECIST)disease unless/until Tumor Burden increases by 20% (ie the sum of thediameters at nadir of target lesions and any new measurable lesionsincreases by the required amount). Non-target lesions are not consideredin the definition of Stable Disease and Partial Response.

Patients treated according to the methods disclosed herein preferablyexperience improvement in at least one sign of cancer. In oneembodiment, improvement is measured by a reduction in the quantityand/or size of measurable tumor lesions. In another embodiment, lesionscan be measured on chest x-rays or CT or MRI films. In anotherembodiment, cytology or histology can be used to evaluate responsivenessto a therapy.

In one embodiment, the patient treated exhibits a complete response(CR), a partial response (PR), stable disease (SD), immune-relatedcomplete disease (irCR), immune-related partial response (irPR), orimmune-related stable disease (irSD). In another embodiment, the patienttreated experiences tumor shrinkage and/or decrease in growth rate,i.e., suppression of tumor growth. In another embodiment, unwanted cellproliferation is reduced or inhibited. In yet another embodiment, one ormore of the following can occur: the number of cancer cells can bereduced; tumor size can be reduced; cancer cell infiltration intoperipheral organs can be inhibited, retarded, slowed, or stopped; tumormetastasis can be slowed or inhibited; tumor growth can be inhibited;recurrence of tumor can be prevented or delayed; one or more of thesymptoms associated with cancer can be relieved to some extent.

In other embodiments, administration of effective amounts of theanti-ICOS antibody (or combinations of anti-ICOS antibody and at leastone additional antibody, e.g., an anti-PD-1 antibody or anti-CTLA-4antibody) according to any of the methods provided herein produces areduction in size of a tumor, reduction in number of metastatic lesionsappearing over time, complete remission, partial remission, or stabledisease. In still other embodiments, the methods of treatment produce acomparable clinical benefit rate (CBR=CR+PR+SD≥6 months) better thanthat achieved by an anti-ICOS antibody alone (or any one of the combinedantibodies alone). In other embodiments, the improvement of clinicalbenefit rate is about 20% 20%, 30%, 40%, 50%, 60%, 70%, 80% or morecompared to the anti-ICOS antibody alone (or any one of the combinedantibodies alone).

Vaccine Adjuvants

Anti-huICOS antibodies described herein can be used to enhanceantigen-specific immune responses by co-administration of an anti-huICOSantibody with an antigen of interest, e.g., a vaccine. Accordingly,provided herein are methods of enhancing an immune response to anantigen in a subject, comprising administering to the subject: (i) theantigen; and (ii) an anti-huICOS antibody, or antigen-binding fragmentthereof, such that an immune response to the antigen in the subject isenhanced. The antigen can be, for example, a tumor antigen, a viralantigen, a bacterial antigen or an antigen from a pathogen. Non-limitingexamples of such antigens include those discussed in the sections above,such as the tumor antigens (or tumor vaccines) discussed above, orantigens from the viruses, bacteria or other pathogens described above.

Detection and Diagnostics

In another aspect, provided herein are methods for detecting thepresence of human ICOS antigen in a sample, or measuring the amount ofhuman ICOS antigen, comprising contacting the sample, and a controlsample, with an anti-ICOS antibody, e.g., a monoclonal anti-human ICOSantibody, or an antigen binding fragment thereof, that specificallybinds to human ICOS, under conditions that allow for formation of acomplex between the antibody or fragment thereof and human ICOS. Theformation of a complex is then detected, wherein a difference complexformation between the sample compared to the control sample isindicative the presence of human ICOS antigen in the sample. Moreover,the anti-ICOS antibodies described herein can be used to purify humanICOS via immunoaffinity purification.

The present disclosure is further illustrated by the following examples,which should not be construed as limiting. The contents of all figuresand all references, Genbank sequences, patents and published patentapplications cited throughout this application are expresslyincorporated herein by reference.

EXAMPLES

The following are non-limiting examples of antibodies, compositions andmethods of the invention. It is understood that various otherembodiments may be practiced consistent with the general descriptionprovided herein.

Example 1 Generation of Fully Human Anti-huICOS Antibodies

Fully human anti-huICOS monoclonal antibodies, and fully humanantibodies that bind to the same epitope and/or cross-block the bindingof the fully human anti-ICOS antibodies are disclosed herein. Suchantibodies may be generated using transgenic mice that express humanantibody genes, as described in the following example.

A. Hybridoma Technology Using HuMab Mouse® and/or a Kunming (KM) Mouse®

Anti-ICOS Antibodies were Generated

Human anti-ICOS monoclonal antibodies were generated by immunizing theHC2/KCo7 strain of HuMAb® transgenic mice (“HuMAb®” is a trademark ofMedarex, Inc., Princeton, N.J.) and KM mice (the KM Mouse® straincontains the SC20 transchromosome as described in WO 02/43478) with 1) asoluble human ICOS antigen and 2) a Hek293T cell line that wastransfected with human ICOS gene that expresses human ICOS, a ChineseHamster Ovary (CHO) cell line that expresses ICOS, and a 300-19 cellline that expresses ICOS. HC2/KCo7 HuMAb mice and KM mice were generatedas described in U.S. Pat. Nos. 5,770,429 and 5,545,806, the entiredisclosures of which are hereby incorporated by reference.

Antigen and Immunization

The antigens were a soluble fusion protein comprising an ICOSextracellular domain fused with an antibody Fc domain (recombinant humanICOS-mouse Fc chimeric protein), Hek293T cells, CHO cells, or 300-19cells that was transfected for surface expression of human ICOS. Theantigens were mixed with RIBI monophosphoryl lipid A (MPL) plus TDMadjuvant system (Sigma) for the immunizations. The mice described abovethat were immunized with the soluble ICOS protein in 15-25 μg solublerecombinant ICOS antigen in PBS or 1×10⁷ CHO cells, Hek293T cells, or300-19 cells transfected for surface expression of human ICOS in PBSwere mixed 1:1 with the adjuvant. Mice were injected with 200 μl of theprepared antigens into the peritoneal cavity or subcutaneous or foot padevery two to fourteen days. Mice were injected with 100-200 μl ofrecombinant moue IL21 following the ICOS antigen immunizations. Micethat developed anti-ICOS titers were given an intravenous injectionand/or foot pad injection of 10-20 μg soluble recombinant ICOS antigenor 5×10⁶ CHO cells, or 300-19 cells transfected for surface expressionof human ICOS or plus intraperitoneal injection of 15 μg recombinantmouse IL21 protein in 100 μl of PBS three to two days prior to fusion.Mouse lymph nodes and or spleens were harvested, and the isolated lymphnode cells and/or splenocytes were used for hybridoma preparation.

Selection of HuMab Mouse® or KM Mouse® that Produced Anti-ICOSAntibodies

To select a HuMab Mouse® or KM Mouse® that produced ICOS-bindingantibodies, sera from immunized mice was tested by enzyme-linkedimmunosorbent assay (ELISA). Briefly, microtiter plates were coated withpurified recombinant human ICOS-mouse Fc at 1-2 μg/ml in PBS; 50μl/wells were incubated 4° C. overnight, then blocked with 200 μl/wellof 5% chicken serum in PBS/Tween (0.05%). Dilutions of plasma fromICOS-immunized mice were added to each well and incubated for one hourat ambient temperature. The plates were washed with PBS/Tween and thenincubated with a goat-anti-human IgG Fc polyclonal antibody conjugatedwith horseradish peroxidase (HRP) for one hour at room temperature.After washing, the plates were developed with ABTS substrate (Moss Inc.,product: ABTS-1000) and analyzed by spectrophotometer at 415-495 OpticalDensity (OD). Sera from immunized mice were then further screened byflow cytometry for binding to a cell line that expressed human ICOS, butnot to a control cell line that did not express ICOS. Briefly, thebinding of anti-ICOS antibodies was assessed by incubatingICOS-expressing CHO cells or 300-19 cells with the anti-ICOS antibody at1:20 dilution. The cells were washed and binding was detected with aphycoerythrin (PE)-labeled anti-human IgG antibody. Flow cytometricanalyses were performed using a FACScan™ flow cytometer (BectonDickinson, San Jose, Calif.). Mice that developed the highest titers ofanti-ICOS antibodies were used for fusions. Fusions were performed asdescribed below. Hybridoma supernatants were tested for anti-ICOSactivity by ELISA and fluorescence-activated cell cytometry (FACS).

Hybridoma Preparation

The mouse splenocytes and/or lymphocytes isolated from a HuMab Mouse®and/or a KM Mouse® were fused with a mouse myeloma cell line usingelectric field-based electrofusion using a Cyto Pulse large chamber cellfusion electroporator (Cyto Pulse Sciences, Inc., Glen Burnie, Md.).Briefly, single cell suspensions of splenic lymphocytes from immunizedmice were fused to equal number of Sp2/0 non-secreting mouse myelomacells (ATCC, CRL 1581 cell lines). Cells were plated at approximately2×10⁴/well in flat bottom microtiter plates, followed by about two weeksincubation in selective medium containing 10% fetal bovine serum, 10%P388D1 (ATCC, CRL TIB-63) conditioned medium, 3-5% Origen (IGEN) in DMEM(Mediatech, CRL 10013, with high glucose, L-glutamine and sodiumpyruvate) plus 5 mM HEPES, 0.055 mM 2-mercaptoethanol, 50 mg/mlgentamycin and 1× hypoxanthine-aminopterin-thymidine (HAT) medium(Sigma, CRL P-7185). After one to two weeks, cells were cultured inmedium in which the HAT was replaced with hypoxanthine and thymidine(HT) medium. Approximately 10-14 days after cell plating, supernatantsfrom individual wells were screened first for whether they containedhuman gamma and kappa antibodies. The supernatants that were scoredpositive for human gamma and kappa antibodies were then subsequentlyscreened by ELISA and FACS for human anti-ICOS monoclonal IgGantibodies. The antibody-secreting hybridomas were transferred to24-well plates, screened again and, if still positive for humananti-ICOS monoclonal antibodies, were subcloned at least twice bylimiting dilution. The stable subclones were then cultured in vitro togenerate small amounts of antibody in tissue culture medium for furthercharacterization. The human monoclonal antibodies produced were thenpurified by protein A column chromatography. Isolated antibodies ofparticular interest were designated as 17C4, 9D5, 3E8, 1D7-a, and 1D7-b,as described in Table 7 below.

TABLE 7 Isolated Antibodies Heavy Chain Light Chain Heavy Chain LightChain CDR 1, CDR 1, Variable Variable Antibody 2, and 3 2, and 3 DomainDomain Name SEQ ID NOs SEQ ID NOs SEQ ID NO SEQ ID NO 17C4 18, 19, and20 21, 22, and 23 16 17 9D5 26, 27, and 28 29, 30, and 31 24 25 3E8 34,35, and 36 37, 38, and 39 32 33 1D7-a 42, 43, and 44 45, 46, and 47 4041 1D7-b 42, 43, and 44 49, 50, and 51 40 48

B. PROfusion® mRNA Display System

KM mice #333819 and #333821 were immunized with CHO cells overexpressinghuman ICOS, and the spleen and lymph nodes were subsequently harvested.Total RNA was extracted from the spleen and lymph node cells and wasreverse transcribed using primers specific to antibody constant regions.The antibody cDNA was used to generate a single-chain variable fragment(scFv) library that was expressed in mRNA display, where each scFvprotein was fused to its encoding mRNA via a puromycin linkage. Thelibrary was selected against 10 nM recombinant human ICOS-Fc, and anybound molecules were recovered using capture with Protein G magneticbeads and amplified by polymerase chain reaction (PCR) to proceed intothe next round. A total of six rounds were completed, after which asignificant ICOS binding signal was observed by quantitative PCR (qPCR).The final population was sequenced and unique variable regions werecloned into IgG expression vectors. IgG proteins were expressed usingtransient transfection of Hek293T cells to generate material for bindingand functional assays. Antibody IgG-2644, as described in Table 8 below,was selected.

TABLE 8 Antibody IgG-2644 Heavy Chain Light Chain Heavy Chain LightChain Heavy Chain Light Chain Antibody CDR 1, 2, and 3 CDR 1, 2, and 3Variable Domain Variable Domain Domain Domain Name SEQ ID NOs SEQ ID NOsSEQ ID NO SEQ ID NO SEQ ID NO SEQ ID NO 2644 191, 192, and 194, 195, and186 189 185 188 193 196

Example 2 Generation of Humanized Anti-ICOS Antibodies

Sequence Determination of Hamster ICOS Antibody C398.4A

A hamster anti-rat ICOS monoclonal antibody, C398.4A (anti-H4/ICOS)Monoclonal Antibody, referred to herein as “parental hamster antibody”or antibody “C398.4A,” was obtained from BioLegend®. The C398.4Aantibody was sequenced using mass spectrometry. Specifically, C398.4Awas denatured in 5.3 M guanidine HCl, reduced with dithiolthreitol (40mM), and alkylated with iodoacetamide (80 mM). After desalting with a 6kDa MW cutoff Zeba desalting column, the antibody was enzymaticallydigested with trypsin, chymotrypsin, pepsin, Lys-C, AspN, or GluC andanalyzed by mass spectrometry. Peptide mapping and MS/MS was used toidentify the resulting peptides and to confirm the amino acid sequence.The intact heavy and light chain masses were generated by cleaving theglycan off with PNGaseF, reducing the antibody with dithiolthreitol, andalkylating with iodoacetic acid. The resulting antibody chains wereanalyzed by LC-MS.

The resulting peptide fragmentation data was aligned to a custom proteindatabase consisting of three light chain and heavy chain antibodysequences for Cricetulus migratorius present in GenBank along withantibody sequences determined in-house through RNA sequencing ofmonoclonal antibodies derived from Armenian hamsters. A database searchidentified the GenBank sequence gene locus CMU17870 (Accession U17870)as similar to the C398.4A light chain. Amino acid substitutions in CDR3and the framework region were observed in the C398.4A sequence whencompared to the CMU17870 light chain sequence. The database searchidentified the GenBank sequence gene locus CMU17166 (Accession U17166)as similar to the C398.4A heavy chain variable region. The J-regionmatched an internally identified hamster sequence HA-VH-7. The constantregion of the heavy chain matched the same isotype as the antibodyHL4E10 (Accession HM369133). The D-region was determined to be novel andwas identified by de novo sequencing of the peptide fragmentation data.Amino acid substitutions in CDR1, CDR2, CDR3, and the variable frameworkregion were observed when compared to the CMU17166 and HA-VH-7 heavychain sequences.

Generation and Evaluation of Chimeric Antibody ICOS.4 Based on AntibodyC398.4A

The C398.4A antibody protein sequence was back-translated into cDNAsequence. The isoleucine/leucine (I/L) residue at position 96 in the Dregion (CDRH3) was expressed with either isoleucine or leucine at thisposition. The variable regions were cloned into expression vectorscontaining a signal sequence and human IgG1f constant regions, andtransfected into CHO-S cells for the expression of chimeric humanantibody, ICOS.4. The chimeric antibody were purified using 2 Lsupernatant each using 250 mL Protein A column on the AKTA Avant andwere screened for activity in the CHO-OKT3-CD32a/CD25−CD4+ T cell assay.The CHO-OKT3-CD32a/CD25−CD4+ T cell assay was a co-culture of irradiated(growth arrested) CHO cells transfected with a low level ofsingle-chain-CD3 (clone OKT3) and a higher level of CD32A (to cross-linkantibody) with CD25-depleted-CD4+ T cells at a CHO:T cell ratio of 1:4.The CHO cell line was grown in shaker flasks and irradiated on the dayof assay set-up. The T cells were selected from a fresh buffy coat(Stanford Blood Bank) using the RosetteSep® CD4+ T cell isolation kit(Catalog 15062) followed by depletion of CD25+ cells using the Miltenyi®CD25-microbeads (Catalog 130-092-983), following kit instructions fordepletion on the AutoMACS®.

ICOS antibody or isotype control were titrated from 5 μg/mL by 5-foldserial dilutions, with each condition set up in triplicate. The cultureswere set up in flat-bottom TC-treated Costar® 96-well plates with 5×10⁴T cells and 1.25×10⁴ CHO cells in 200 μL complete medium (RPMI-1640(Corning®, Catalog 10-040-CM)+10% fetal bovine serum (FBS) (Gibco®,Catalog 25140)+1× Pen Strep (Corning Catalog 30-002-CL)+10 mM HEPES(Corning Catalog 25-000-CL)+1 mM sodium pyruvate (Corning Catalog25-000C1)+1×MEM (Corning Catalog 25030-CL) per well and incubated forthree days at 37° C. and 5% CO₂.

Culture supernatants (50 μL/well) were harvested at Day 3 for analysisof interferon-gamma concentrations using homogeneous time resolvedfluorescence (HTRF) assay (Cisbio®), reading out using the Rubystar®microplate reader, and calculating the concentrations from a standardcurve using Softmax Pro® software. ICOS.4 antibody was tested in afunctional T cell assay using CHO-OKT3-CD32 and CD4+ CD25−T cells withthe antibody titrated to compare the relative levels of dose-dependentco-stimulation, as measured by interferon-gamma secretion. ICOS.4exhibited an EC50 value of 0.018 μg/mL.

Isotype Selection

Isotype selection for immuno-oncology therapeutic antibodies and,specifically, for agonist targets, is influenced by two differentconsiderations downstream of binding to FcRs. As detailed by Ravetch andcolleagues (Li and Ravetch, Science 2011; 333:1030-4; Otten et al., JImmunol. 2008; 181:6829-36), binding of antibodies to activatingreceptors can lead to antibody-dependent cell-mediated cytotoxicity(ADCC) or antibody-dependent cellular phagocytosis (ADCP) of cellsexpressing the target. On the other hand, binding of antibodiespreferentially to the inhibitory FcR can mediate multivalentcrosslinking of the receptor and agonist signaling. Because ICOS can behighly expressed on CD8+ and CD4+ Teffs in the tumor microenvironment,use of an isotype that can mediate ADCC or ADCP was considered a lessattractive option. In vitro ADCC activity of anti-ICOS antibodies alsosuggested that the anti-ICOS antibodies were highly competent atmediating ADCC and supported the idea that ADCC-inducing isotypes shouldbe avoided. Antibodies that increase the affinity of human IgG1 forCD32B were instead considered as alternative isotypes. The isotypesconsidered were the IgG1 S267E mutation, SELF mutations, and V12mutations of the human IgG1, as shown in Table 3 above. These mutationsall increase affinity for CD32B and to varying degrees CD32A, whiledecreasing the affinity for CD16 (as shown in Table 9). This decreasewas predicted to lower ADCC activity, as this is the FcR likelymediating depletion of T cells in the tumor.

TABLE 9 Comparison of Binding Properties of Wild Type and S267E Variantof Human IgG1 (μM Kd) Protein IgG1f IgG1f-S267E CD16-V 97 950 CD16-F200 >5000 CD32A-H131 530 650 CD32A-R131 960 31 CD32B 3400 87 CD64 0.20.2 C1q + ++

In vitro activity in the SEB assay using CD4+ T cells and B cells showedsuperior activity of the IgG1f S267E antibody compared to the human IgG1and other isotypes, as described above. Based on the data from thesefunctional experiments, IgG1f S267E was chosen as the lead antibody. Onecomplication in the choice of IgG1f S267E was that this isotype binds tocomplement C1q with higher affinity than the human IgG1, which posed apossible increased risk of complement dependent cytolysis (CDC).Surprisingly, IgG1f S267E did not have higher CDC activity compared tohuman IgG1 in in vitro testing. Therefore, the S267E mutation did notresult in an increased risk of CDC.

Humanization of Antibody ICOS.4

Antibody ICOS.4 was humanized by grafting hamster CDRs onto humangermline genes (FIG. 3), VH3-15 was selected for the heavy chain and VKIO18 was selected for the light chain based on framework sequencehomology. Human germline FW4, JK3, was also selected for the light chainbased on sequence homology. Human germline FW4, JH4, was selected forthe heavy chain based on sequence similarity, and it did not containresidues that could pose a potential liability risk. A panel of 26antibodies was evaluated in the CHO-OKT3-CD32A/CD4+ CD25− T cell assay,with an antibody range starting at 0.2 μg/mL and titrated by four-folddilutions, to identify humanized sequences that retain binding similarto the parental hamster antibody (C398.4A, i.e., the parental hamsterantibody having heavy and light chain region sequences set forth in SEQID NOs: 3 and 4, respectively).

One amino acid residue substitution was identified (T94A) to restorebinding of the humanized CDR grafted antibody, and it is located at thejunction of FR3 and CDRH3. In addition, three chimeric antibodies withliability mutations at the D56, G57 sequence were also evaluated to seeif the potential isomerization site in the VL could be removed withoutaffecting activity. The residue substitution D56E was selected toeliminate the potential isomerization site (D56, G57) in the light chainand incorporated into the humanized sequence. The humanized antibodieswere screened with the IgG1f isotype, however, ICOS.33 IgG1f S267E wasre-expressed using the IgG1f S267E isotype. A description of theantibodies generated is provided in Table 10 below.

TABLE 10 Summary of Antibodies Generated Antibody Name Description 1C398.4A Parental hamster antibody 2 ICOS.1 mG1 Mouse IgG1 anti-mouseICOS antibody derived from rat 17G9 (does not bind to human ICOS) 3ICOS.4 Chimeric antibody with variable regions of C398.4A made as fourdifferent variants (listed below) 4a ICOS.4 mG1 Mouse IgG1 variant ofICOS.4 4b ICOS.4 mIgG2a Mouse IgG2a variant of ICOS.4 4c ICOS.4 hg1Human IgG1 variant of ICOS.4 4d ICOS.4 hg1 SE Human IgG1 variant ofICOS.4 with S267E mutation 5 ICOS.33 Humanized (IgG1 isotype) ICOS.4with parental CDRs grafted onto human framework and T94A and D56Emutations 6 ICOS.33 IgG1f ICOS.33 with S267E substitution S267E 7ICOS.34 G1f Humanized (IgG1 isotype) ICOS.4 with parental CDRs graftedonto human framework (also referred to as “C398.4A-03”) 8 ICOS.35 G1fICOS.34 plus T94A mutation

A set of four humanized antibodies based on C398.4A were tested in theCHO-OKT3-CD32a/CD4+ CD25− T cell functional assay, comparing to theoriginal hamster chimeric antibody, as described below in Example 3.ICOS.33 IgG1f S267E was selected for further characterization anddevelopment. The heavy and light chain variable region sequences forICOS.33 IgG1f S267E are shown in SEQ ID NOs: 5 and 6, respectively, andin FIG. 4.

Example 3 Antibody Selection

CHO-scFv-CD3-CD32A/CD25−CD4+ T Cell Assay

Initial functional assay screening was performed using CHO cellsexpressing single-chain variable fragment (scFv) anti-CD3 (OKT3) andhuman CD32A to stimulate primary human T cells. This assay was aco-culture of irradiated (growth arrested) CHO cells transfected with alow level of single-chain variable fragment-CD3 (clone OKT3) and ahigher level of CD32A (to cross-link antibody) with CD25-depleted-CD4+ Tcells at a CHO:T cell ratio of 1:4. The CHO cell line was grown inshaker flasks and irradiated on the day of assay set-up. The T cellswere selected from fresh buffy coats (Stanford Blood Bank) using theRosetteSep CD4+ T cell isolation kit. CD25+ cells were depleted usingMiltenyi CD25-microbeads, following kit instructions for depletion onthe AutoMACS.

ICOS antibody or isotype control (i.e., antibody of the same isotype asthe ICOS antibody, but that does not bind any naturally-occurring humanprotein, e.g., antibodies against keyhole limpet hemocyanin (KLH),diphtheria toxin, amongst others) was titrated from 2 jag/mL byfive-fold serial dilutions, with each condition set up in triplicateusing T cells from two donors. The cultures were set up in flat-bottomTC-treated 96-well plates (Costar) with 5×10⁴ T cells and 1.25×10⁴ CHOcells in 200 μL complete medium per well and incubated for three days at37° C. and 5% CO₂.

Culture supernatants (50 μL/well) were harvested on Day 3 for analysisof interferon-gamma (IFN-γ) concentrations using the homogeneous timeresolved fluorescence (HTRF) assay (Cisbio). Concentrations weredetermined using the Rubystar microplate reader and calculated from astandard curve using Softmax Pro software. The plates were then pulsedwith 0.5 μCi tritiated thymidine per well for eight hours and frozen.The cells were harvested onto filter plates (Perkin Elmer) for analysisof tritiated thymidine incorporation to assess proliferation.

The FcR CD32A permitted crosslinking of antibodies regardless ofantibody Fc subtype. This crosslinking allowed for the costimulation ofT cells through ICOS agonism, resulting in enhanced proliferation andcytokine release in comparison to isotype control-treated cells. Thisactivity was seen on CD8+, CD4+, and CD25− CD4+ T cells. Because ofsuperior signal-to-noise in the depleted CD25− CD4+ T cell assay, thesecells were used for screening hybridomas. The best performing antibodieswere selected for sub-cloning, purification, and furthercharacterization. The parental hamster monoclonal antibody was includedin the analysis of the panel of antibodies. As described above, activityin the CHO-CD3-CD32 assay was used to select a lead panel of antibodies,which were re-expressed as human IgG1 antibodies or other modifiedversions of human IgG1. ICOS.33 IgG1f S267E exhibited dose-dependentinduction of IFN-γ secretion and proliferation in theCHO-scFv-CD3-CD32A/CD25−CD4+ T cell assay, as shown in FIG. 5. The meanEC50 of this effect was 0.083 nM (+0.067, n=6) for proliferation and0.083 nM (+0.074, n=6) for IFN-γ induction. Proliferation inductionranged from 2- to 5-fold at the three highest concentrations tested in atotal of 6 donors, while IFN-γ induction ranged from 2-fold to 9-fold inthe same experiments compared to control. Previous experiments usingCHO-scFv-CD3 (no CD32A) confirmed that cross-linking is required foragonistic activity of all ICOS antibodies tested.

CD25−CD4+ T Cell and B Cell-SEB Assay

Further characterization of anti-ICOS antibodies functional activity wasperformed using Staphylococcal Enterotoxin B (SEB) as a T cell receptor(TCR) stimulus and addition of anti-ICOS antibodies to test forco-stimulation. When human peripheral blood cells (PBMC) were used inthe assay, anti-ICOS antibodies showed no functional activity. However,when CD4+ T cells (either CD25-depleted or total CD4+ T cells) were usedalong with purified B cells, anti-ICOS antibodies showed enhancedinterferon gamma (IFN-γ) secretion compared to control antibodies.

This assay involved a co-culture of autologous CD25−CD4+ T cells and Bcells. SEB was added to a final fixed concentration of 85 ng/mL toprovide submaximal stimulation, and ICOS antibody was titrated to show adose-dependent costimulation effect. The purpose of this assay was tomeasure the ability of ICOS antibodies to enhance activation of T cellsin the context of a primary activating signal (SEB+B cells) as evidencedby levels of IFN-γ induction. It is beneficial to induce higher levelsof IFN-γ because it is a measure of T cell activation that reflects thepotency of the different antibodies exhibiting agonism of the ICOSreceptor, and IFN-γ is a known mediator of anti-tumor immunity.

T cells were isolated by positive selection from two fresh buffy coatsfollowed by detachment of beads to generate untouched CD4+ T cells(Invitrogen). CD25+ cells were then depleted from the CD4+ T cells usingCD25-microbeads (Miltenyi), following kit instructions for depletionusing the AutoMACS. The negative fractions from the CD4 isolations werethen used to isolate the autologous B cells using Miltenyi CD20 beads,following kit instructions for positive selection using the AutoMACS.

The T cells were plated in 96-well flat-bottom TC-treated culture platesat 5×10⁴ cells/well with autologous B cells at 3 to 5×10⁴ cells/well(depending on yield from each donor) with SEB included for a finalconcentration of 85 ng/mL. ICOS antibody or isotype control was titratedfrom 5 μg/mL by 5-fold serial dilutions for a total of seven points,each tested in triplicate. The assay was set up in complete medium with200 μL/well final volume. The plates were incubated for 3 days at 37° C.and 5% CO₂.

Culture supernatants (50 μL/well) were harvested on Day 3 for analysisof IFN-γ concentrations using the HTRF assay (Cisbio). Concentrationswere determined using the Rubystar microplate reader and calculated froma standard curve using Softmax Pro software.

SEB co-culture experiments compared IFN-γ production for anti-ICOSantibodies ICOS.33 IgG1f, ICOS.33 IgG1f S267E, 9D5 IgG1f, 9D5 IgG1fS267E, 2644 IgG1f S267E, and control antibody KLH control Ig1f (FIG. 6).The humanized lead antibody ICOS.33 with the S267E mutation (ICOS.33 IgGIf S267E, as depicted in the full downward triangle in FIG. 6) inducedhigher levels of IFN-γ than the same antibody with wild type Fc (ICOS.33IgG1f). The other comparator antibodies tested, that is, 95D IgG1f, 9D5IgG1f S267E, and 2644 IgG1, also exhibited lower activity than ICOS.33IgG1f S267E. The KLH control Ig1f did not exhibit any activity. ICOS.33IgG1f S267E antibody increased IFN-γ production up to 2.3-fold comparedto the control antibody in a dose-dependent manner in CD25−CD4+ T and Bcell co-cultures stimulated by a suboptimal dose of SEB. A total of 20donors were tested using this assay, all showing the greatest agonistactivity by ICOS.33 IgG1f S267E, with an EC50 of 0.020 nM (+0.018).

The activity of ICOS antibodies on T follicular helper cells (Tfhs) wastested in this manner. Compared to control antibody 1D12, enhancedsecretion of IL-10 was observed after adding the anti-ICOS antibodies9D5 and ICOS.4. Tfh cells were sorted from PBMCs after enrichment by CD4selection (Invitrogen kit) by staining the CD4 enriched cells for CD4,CD14, CXCR5, CD45RA and CD123 and sorting for Tfh cells (CD4+CXCR5+CD45RA-CD123-CD14-) using the Aria II FACS. Naive B cells were isolatedfrom the CD4-negative fraction using the Miltenyi kit. The Tfh and naiveB cells were co-cultured in 96-well flat-bottom TC plates with 5e4cells/well of each and stimulated with SEB for 2 days when IL-10 andIFNγ were measured by ELISA (BD) and shown to be enhanced by ICOSantibodies. This enhanced cytokine secretion did not require anexogenous crosslinker and could be enhanced by including the S267Emutation to the human IgG1 (FIGS. 7A and 7B).

ICOS.33 IgG1f S267E was selected for further development because of itsability to stimulate IFN-γ production in the CHO FcR assay and inducecell proliferation (FIG. 5), as well as its higher functional activityin the SEB assay compared to the other anti-ICOS antibodies tested (FIG.6).

Example 4 Reversal of Regulatory T Cell Suppression by ICOS.33 IgG1fS267E

The objective of this study was to determine the effect of ICOS.33 IgG1fS267E on effector T cell (Teff) proliferation and Treg-mediatedsuppression.

U-bottom plates were coated for three hours at 37° C. with anti-CD3 (3μg/mL) in combination with either ICOS.33 IgG1f S267E (10 μg/mL) oranti-KLH, an isotype control that does not bind ICOS protein (10 μg/mL)in PBS. CD4+ T cells were isolated from whole fresh buffy coats usingRosetteSep CD4+ T enrichment cocktail in conjunction with Ficoll-Paqueseparation, following the RosetteSep manufacturer's instructions.Enriched CD4+ T cells were stained with fluorophore-conjugatedmonoclonal antibodies directed against CD4, CD25, CD127, CD45RA, andCD45RO in FACS sort buffer. CD4+ T cells were then sorted into Teff(CD4+ CD25loCD127hi), RA+ Treg (CD4+ CD25hiCD127lo/CD45RA+/CD45RO−) andRO+Treg (CD4+ CD25hiCD127lo/CD45RA−/CD45RO+) cell populations using aFACSAria II cell sorter. Sorted Tregs were labeled with CellTrace™Violet (CTV) proliferation dye according to manufacturer's instructionsat a concentration of 5 μM. Sorted Teffs were labeled with CellTraceCFSE™ proliferation dye (CFSE) according to manufacturer's instructions,except that it was used at a higher dilution of 1.25 μM to reducecytotoxic effects observed in previous experiments.

Fifty-thousand sorted and CFSE-labeled Teffs in 100 μL of completemedium were added to each well of the 96-well plate coated with anti-CD3and ICOS.33 IgG1f S267E or isotype control. These were prepared with orwithout anti-CD28 added at 2 jag/mL (for a final concentration of 1μg/mL). Titrating numbers of sorted and CTV-labeled Tregs in 100 μL ofcomplete medium were then added to each well beginning with 5×10⁴ Tregs(1:1 Treg to Teff) and decreasing 2-fold in subsequent wells (1:2, 1:4,etc).

The cultures were incubated for six days at 37° C. when the cells werestained with the fixable viability dye Ghost Red-780 to exclude deadcells. Flow cytometry data were collected using a BD FACSCanto II flowcytometer. Percent Teff proliferation was determined using FACSDiva flowcytometry analysis software. The percent proliferation of Teffs wasdetermined by gating on Teffs that had diluted their CellTrace CFSEproliferation dye following at least one round of division.

This Example showed that ICOS.33 IgG1f S267E both reversed Treg-mediatedsuppression and enhanced Teff proliferation, as shown in FIGS. 8A and8B. The values shown in the legend in FIGS. 8A and 8B are the Teff:Tegratios. Hence, a value of 1 means a ratio of 1 Teff to 1 Treg, a valueof 2 means 2 Teff to 1 Treg, and so on, essentially titrating down theTregs. At the 1:1 ratio, ICOS.33 IgG1f S267E showed an approximately4-fold increase of proliferation and apparent reversal of RA+Treg-mediated suppression. A 7-fold increase in proliferation andapparent reversal of RO+ Treg mediated suppression, as measured by thedifference in percent of dividing Teff between isotype control and ICOSantibody, was also observed. As the Tregs were titrated out, there was aproportional decrease of apparent suppression and in the absence of Tregthere was approximately a 1.5-fold increase in the percent of dividedTeff relative to the isotype control. The effect in the presence of Tregcould be a result of decreasing Teff susceptibility to Treg suppressionor a decreasing suppressive capacity of Tregs. It is beneficial thatICOS.33 IgG1f S267E reversed Treg-mediated suppression and enhanced Teffproliferation, as this showed that ICOS.33 IgG1f S267E stimulated theimmune response.

Example 5 In Vitro Fc Effector Function of ICOS.33 IgG1f S267E

The objective of this study was to assess the antibody-dependentcellular cytotoxicity (ADCC) and complement C1q factor bindingactivities of ICOS.33 IgG1f S267E.

Target Cell Labeling with Calcein AM

CD4+ T cells from Donor 2 (Stanford Blood ID WO70516511239) wereisolated, activated and labeled with Calcein AM. Briefly, peripheralblood mononuclear cells (PBMC) were purified from heparinized buffy coatby density gradient centrifugation and washed with phosphate bufferedsaline (PBS) supplemented with 2% FBS (HyClone). CD4+ T cells wereisolated by negative selection using a magnetic bead-based separationkit (StemCell Technologies) and automated RoboSep cell separator(StemCell Technologies). From the CD4+ T cell isolation, CD25+ Tregswere depleted using a magnetic bead-based separation kit (MiltenyiBiotec). Purified CD4+ T cells were re-suspended at 2.5×10⁶ cells/mL inR10 media and activated with the T Cell Activation/Expansion kit(Miltenyi Biotec) at one bead per two cells for three days at 37° C. Onday 3, cells were counted, pelleted, and re-suspended at 1×10⁶ cells/mLin PBS in a 15 mL conical tube. Calcein AM reagent was prepared byadding 20 μL of ultrapure DMSO to the reagent tube containing 50 μg oflyophilized reagent. A volume of 2 μL of reconstituted Calcein AM wasadded to the suspended cells for every 1 mL of volume. The cells werevortexed and placed in a 37° C. incubator for 30 minutes. After theincubation period, the labeled target cells were washed three times withADCC assay media, and their concentration was adjusted to 10⁵ cells/mLin assay media.

Antibody-Dependent Cellular Cytotoxicity (ADCC) Assay with ActivatedCD4+ T Cells as Targets

Primary human NK effector cells were purified from fresh PBMC from twodifferent donors (BDC Donors 9 and 12) and stimulated with IL-2.Briefly, PBMC were purified from heparinized whole blood samples bydensity gradient centrifugation and washed with PBS supplemented with 2%FBS (HyClone). NK cells were isolated from PBMC by negative selectionusing a magnetic bead-based separation kit (Miltenyi Biotech) andautoMACs Separator (Miltenyi Biotech). Purified NK cells werere-suspended at 1×10⁶ cells/mL in MyeloCult media supplemented with 500IU/mL IL-2 and incubated overnight at 37° C.

The following day, activated NK effector cells were washed twice inassay media and their concentration was adjusted to 4.33-5×10⁵ cells/mLin assay media. Labeled target cells (50 μL/well) were added to aU-bottom 96-well plate containing 50 μL/well of test or controlantibody. Activated NK effector cells were then added (100 L/well) toresult in a final effector cell-to-target cell ratio (E:T) of 10:1 and afinal antibody concentration ranging from 0.0002 μg/mL to 1 μg/mL. Theplate was then placed in a humidified 37° C. incubator for two hours.Supernatant (50 μL/well) was transferred into an optical 96-well blackplate, and fluorescence intensity was read on an EnVision plate readerset to 485 excitation and 535 emission filters.

Target cells incubated with effector cells in the absence of antibodyprovided the control for background of antibody-independent lysis(spontaneous lysis), while target cells lysed with 20 μL or 100 μL/wellDelfia Lysis buffer represented maximal release in the assay.

The percentage of antibody-dependent cell lysis was calculated based onmean fluorescence intensity (MFI) with the following formula:

$\left( \frac{{{test}\mspace{14mu}{MFI}} - {{mean}\mspace{14mu}{background}}}{{{mean}\mspace{14mu}{maxium}} - {{mean}\mspace{14mu}{backgrond}}} \right) \times 100$

Percentage of target cell lysis was plotted for each antibody usingPrism v5.01 software from GraphPad Inc.

Results

Primary NK ADCC with Activated CD4+ T Cells as Targets

Anti-ICOS antibody ICOS.33 IgG1f S267E was tested for its ability toinduce ADCC of ICOS-expressing CD4+ T cells as targets and compared ADCCinduced by ICOS.33 IgG1. Two experiments were run with target cells andNK cell donor pairs. In each case, ICOS.33 IgG1f S267E with the modifiedIgG1 isotype induced less ADCC of activated CD4+ T cells than ICOS.33IgG1. Data from these experiments are summarized in Table 11 and FIGS.9A and 9B.

TABLE 11 Comparison of ADCC Mediated by Anti- ICOS IgG1 and ModifiedIgG1Isotypes CD4+ Target Effector Concen- Percent Target Cell Lysis CellCell tration Well Well Well Donor Donor Antibody (μg/mL) 1 2 3 2 12ICOS.33 1.0000 31 16 42 IgG1f S267E 0.0625 20 23 26 0.0039 6 1 7 ICOS.33IgG1 1.0000 57 56 55 0.0625 52 47 45 0.0039 42 38 29 Isotype Control1.0000 16 13 18 2 9 ICOS.33 1.0000 41 −11 16 IgG1f S267E 0.2500 8 22 10.0625 1 10 −5 0.0156 21 −3 −4 0.0039 17 −1 1 0.0010 7 9 −6 0.0002 8 20−10 ICOS.33 IgG1 1.0000 36 43 62 0.2500 48 29 51 0.0625 61 47 51 0.015659 34 45 0.0039 41 −3 59 0.0010 46 20 27 0.0002 25 −6 9 Isotype Control1.0000 −3 2 −8

C1q Binding Assay

The binding of ICOS.33 IgG1f S267E to human C1q was investigated byELISA. All antibodies were coated on a high-binding immunoassay plate at10 μg/mL in PBS at 50 μL per well. A nonspecific binding control withwells coated with PBS only was included. The plate was incubatedovernight at 4° C. The next day, the plate and all reagents wereequilibrated to room temperature; all subsequent steps were performed atambient room temperature. Unoccupied protein binding sites were blockedwith SmartBlock® at 200 μL per well for 30 minutes. The plate was washed3 times with washing solution (PBS+0.05% Tween-20) at 200 μL/well.Graded doses of human C1q (48.00 to 0.76 μM) in ELISA assay buffer wereadded at 50 μL/well. The plate was incubated for two hours and washedthree times with washing solution. Binding of human C1q to theimmobilized antibodies was detected by a biotinylated mouse anti-C1q mAbdiluted 1:1000 in ELISA assay buffer and incubated for one hour. Afterthe plate was washed three times, streptavidin-poly-HRP, diluted 1:5000in conjugate buffer, was added at 50 μL/well and incubated for 30minutes. A final washing step was completed, and the plate was developedwith TMB substrate at 50 μL/well for 5 minutes. The optical density wasread at 650 nm on the SpectraMax 340PC384 Microplate Reader (MolecularDevice). The data was graphed using Prism, Version 5.01.

Results

ICOS.33 IgG1f S267E Binds C1q Component of Human Complement

Anti-ICOS antibody ICOS.33 IgG1f S267E was tested for its ability tobind C1q component of human complement compared to ICOS.33 IgG1 in anELISA assay. ICOS.33 IgG1f S267E was found to bind human C1q with higheraffinity than ICOS.33 IgG1. Data are summarized in FIG. 10 and Table 12.

TABLE 12 ICOS.33 IgG1f S267E Binds Human C1q C1q OD 650 nm (μg/mL)ICOS.33 IgG1 ICOS.33 IgG1f S267E Background 20.000 0.8363 0.8463 0.87040.9977 1.0367 1.0318 0.1168 10.000 0.7742 0.7153 0.7053 0.9207 1.00960.8919 n/a 5.000 0.5254 0.4921 0.5139 0.7107 0.7528 0.7405 n/a 2.5000.3531 0.3600 0.3591 0.5393 0.5667 0.5590 n/a 1.250 0.2561 0.2298 0.23090.4255 0.4460 0.4259 n/a 0.625 0.1724 0.1616 0.1630 0.3306 0.3415 0.3302n/a 0.313 0.1249 0.1260 0.1230 0.2843 0.2784 0.2815 n/a

Conclusion

ICOS.33 IgG1f S267E with a modified IgG1 induced less ADCC-mediatedkilling of ICOS-expressing CD4+ T cells, yet bound with higher affinityto human C1q than an anti-ICOS antibody with wildtype IgG1.

Example 6 In Vivo Anti-Tumor Activity

Antitumor Activity of Anti-Mouse ICOS as Monotherapy or Combined withOther Agents

Variations in the isotype of antibodies that are specific for T cellsurface receptors (both co-stimulatory and co-inhibitory) can alterantitumor activity. Mouse Fc isotype variants of both 17G9 and ICOS.4were generated and expressed as mouse IgG2a isotypes. Both showedsuperior antitumor activity compared to mouse IgG1 variants, asdescribed below. Although not bound by any theory, this was likely dueto depletion of T regulatory cells (Tregs) at the tumor site as well asto effector T cell (Teff) expansion from antibody-mediated agonism ofICOS. Mouse studies with the 17G9 Ab also exhibited downregulation ofICOS receptor on T cell populations both in the spleen and tumor. ICOSexpression was observed to be lower in mice treated with Ab isotypesthat engage FcR (mIgG1 and mIgG2a), while receptor levels were unchangedin the mice treated with a non-FcγR binding Ab (mIgG1 D265A, alsoreferred to as “ICOS.1 D265A”). The dependence on FcγR interactionsuggested that crosslinking is required for this downregulation.Importantly, antitumor activity was demonstrated even though receptorwas downregulated.

Mouse IgG1 variants of both 17G9 (ICOS.1) and of the parental hamsterantibody (ICOS.4), were both expected to have agonist activity due tothe ability to bind to FcRII (inhibitory receptor). As summarized inTable 13, both mouse IgG1 variants demonstrated antitumor activity at adetectable but lower level relative to the IgG2a isotype, and a smallerreduction in tumor Tregs. In contrast, an anti-ICOS antibody that doesnot bind FcRs (17G9-IgG1-D265A) showed no antitumor activity. Although adepleting isotype such as the mouse IgG2a showed higher antitumoractivity than the agonistic mIgG1, the high expression of ICOS on Teffsmakes this mechanism of action less favorable when considered inconjunction with another treatment, such as an anti-CTLA-4 antibodytreatment, which is expected to deplete Tregs more selectively.Consistent with the in vitro findings of better agonist activity inisotypes with the S267E mutation, these isotypes also showed slightlyhigher or equivalent antitumor activity than the human IgG1 in human FcRtransgenic mice.

TABLE 13 Summary of Efficacy Studies Using Anti-Mouse ICOS asMonotherapy or Combined with Other Agents Tumor mAbs Antitumor ActivityColon Anti-ICOS parental-mIgG2a or mIgG1 Monotherapy with anti-ICOSIgG2a 69% TGI, 1/10 CT26 (ICOS.4) TF and with ICOS IgG1 15% TGI, 0/10 TFAnti-PD-1 4H2-mIgG1-D265A Monotherapy 5% TGI, 0/10 TF Combined withanti- Anti-CTLA-4 9D9-mIgG2b ICOS IgG1 83% TGI, 3/10 TF Monotherapy 15%TGI, 0/9 TF Combined with anti- ICOS IgG1 48% TGI, 0/9 TF ColonAnti-ICOS parental-mIgG2a or mIgG1 or Monotherapy with ICOS rat IgG2b25% TGI 0/9 TF MC38 anti-ICOS 17G9 rat IgG2b and with anti-ICOS IgG1 6%TGI, 0/10 TF Anti-PD-1 4H2 mIgG1-D265A Monotherapy 73% TGI, 1/9 TFCombined with anti- ICOS rat IgG2b 92% TGI, 5/9 TF Thymoma Anti-ICOSparental-mIgG2a or mIgG1 Monotherapy with ICOS IgG2a 69% TGI, 2/8 TF EG7and with anti-ICOS IgG1 11% TGI, 1/8 TF Sarcoma Anti-ICOSparental-mIgG2a or mIgG1 Monotherapy with anti-ICOS IgG2a 94% TGI, 0/81956 TF and with anti-ICOS IgG1 50% TGI, 2/10 TF Fibrosarcoma Anti-ICOSparental-mIgG2a or mIgG1 Monotherapy with anti-ICOS IgG2a 84% TGI, 6/10SA1N TF and with anti-ICOS IgG1 55% TGI, 5/10 TF

Antitumor Activity of ICOS IgG1 Fc Variants

To determine if human IgG1 S267E behaves similar to mouse IgG1antibodies, but with more potency with respect to FcR binding to CD32,and agonistic receptor engagement, additional tumor model experimentswere performed. Specifically, to evaluate anti-human ICOS isotypevariants in human Fc receptor (FcR)-transgenic mice, the followingantibodies were constructed:

(a) Anti-ICOS hIgG1—Monoclonal antibody to mouse ICOS, chimerichamster/mouse anti-mouse ICOS, isotype IgG1 (ICOS.4 hg1);

(b) Anti-ICOS hIgG1SE—monoclonal antibody to mouse ICOS, chimerichamster/mouse anti-mouse ICOS, isotype IgG1 SE (ICOS.4 hg1 SE), whichhas a mutation that allows it to bind to CD32R and CD32B better than theunmodified version; and

(c) IgG1 Isotype Control—a fully human IgG1 isotype control (DT-1D12hg1).

MC38 murine colon carcinoma cells were implanted subcutaneously in theright flanks of mice. Mice were divided into three treatment groups anddosed with 60 μg of (1) anti-ICOS IgG1 or (2) anti-ICOS IgG1 SE, or (3)IgG1 isotype control antibody (i.e., antibody of the same isotype as theICOS antibody, but that does not bind any naturally-occurring murineprotein, e.g., antibodies against KLH, diphtheria toxin, amongst others)on Days 7, 10, and 14 post implantation. Body weight and tumor size weremeasured twice weekly through study termination on Day 52. If tumorswere ≥2000 mm³ or appeared ulcerated, the animal was euthanized.Enhancement of antitumor activity was observed with anti-ICOS IgG1 SEmAb treatment at 60 μg per mouse; mean tumor growth inhibition (TGI) was76% compared with 63% for anti-ICOS IgG1 without the SE modification, asshown in Table 14 and FIGS. 11A-C. No significant changes in body weightwere associated with the treatments nor were any overt signs of clinicaltoxicity observed.

Results

In the human FcR-transgenic mice model, administration of ICOS IgG1 SEand ICOS IgG1 mAbs resulted in 76% and 63% mean tumor growth inhibition(TGI), respectively (as shown in Table 14). Five complete regressionswere observed in each group at the dose level (60 μg/mouse) tested(Tables 14 and FIGS. 11A-C). No physical signs of toxicity or bodyweight loss were observed.

TABLE 14 Antitumor Activity of ICOS IgG1 Fc Variants Mean % TGI onComplete Treatment (μg/mouse) Day 30 Regressions^(a) IgG1 IsotypeControl, 60 μg N/A 0/9 Anti-ICOS.4 hg1^(b), 60 μg 63 5/9 Anti-ICOS.4hg1^(c) SE, 60 μg 76 5/9 ^(a)Complete regression = mouse with tumors <20mm³ for at least 3 measurements on last day of study. ^(b)ICOS.4 withhuman IgG1 ^(c)ICOS.4 with human IgG1 and S267E mutation

Conclusions

In a Ravetch syngeneic tumor model study (summarized in Table 15), bothanti-ICOS monotherapies promoted modest antitumor activity, withanti-ICOS IgG1 SE demonstrating slightly greater efficacy at Day 30 (76%vs. 63% mean TGI) (Table 14). No significant changes in body weight wereassociated with the treatments nor were any overt signs of clinicaltoxicity observed. Overall, anti-ICOS monotherapies promoted antitumoractivity, with anti-ICOS IgG1 SE demonstrating slightly greater efficacyat Day 30 (76% vs. 63% mean TGI). Both treatments resulted in five micerejecting their tumor. No significant changes in body weight wereassociated with the treatments nor were any overt signs of clinicaltoxicity observed.

TABLE 15 In vivo Pharmacology Studies Animals Schedule/Route/DurationRange of per Type of Study/ of Study/Vehicle/ Doses group Species/StrainFormulation (μg/mouse) (M/F) Antitumor activity Antibodies administered60 μg/mouse 9 per MC38 tumor IP on post-implantation group; model/humanDays 7, 10, and 14 Human mixed FcγR transgenic IgG1 isotype controlgender C57/B6 mice Anti-ICOS.4 hg1 cohorts Anti-ICOS.4 hg1 SE

Example 7 Sa1N Tumor Model

The Sa1N fibrosarcoma mouse model was used to evaluate antitumoractivity of chimeric anti-ICOS monoclonal antibodies. The ICOS.4 mIgG1is a good surrogate for ICOS.33 IgG1s S267E because this ICOS.4 variantpreferentially binds to the mouse inhibitory Fc receptor. Because thetumor model is performed in a mouse expressing mouse Fc receptor, thismakes the ICOS.4 variant a good surrogate for the human antibody. TheICOS.4 mIgG2a variant is a good surrogate for the ICOS.33 IgG1 antibodybecause this ICOS.4 variant is more similar to human IgG1, as it bindsto the mouse activating Fc receptors. Furthermore, these variants wereparticularly relevant as surrogates, as no modifications were requiredin their variable regions, which already cross-reacted with both mouseand human ICOS protein. In contrast, anti-ICOS.1 murine IgG1 (mIgG1)D265A does not bind FcRs. An IgG1 antibody that does not bind to ICOSprotein was used as an isotype control.

To evaluate antitumor activity in the Sa1N fibrosarcoma model aftertreatment with chimeric anti-ICOS surrogate monoclonal antibodies, Sa1Ncells were implanted subcutaneously in the right flanks of mice. Micewere dosed with mAb in five treatment groups on Days 7, 10, and 14 postimplantation:

(1) chimeric anti-ICOS.1 murine IgG1 (mIgG1) D265A,

(2) anti-ICOS.4 mIgG1

(3) anti-ICOS.4 hIgG1,

(4) anti-ICOS.4 mIgG2a, or

(5) IgG1 isotype control,

-   -   each at 10 mg/kg.

On Day 15, tumor and spleen were harvested from four mice per group forimmuno-monitoring analysis. In the remaining mice, body weight and tumorsize were measured twice weekly through study termination on Day 56. Iftumors were ≥2000 mm³ or appeared ulcerated, animals were euthanized.

On Day 23 post implantation, the last day when the median tumor growthinhibition (TGI) could be calculated based on 60% of treatment groupanimals remaining alive, the treatment efficacy of the anti-ICOSisotypes on Sa1N tumors was evident when compared with isotype controltreatment. Median TGI values were 21% (ICOS.1 mIgG1 D265A), 55% (ICOS.4mIgG1), 69% (ICOS.4 hIgG1), and 84% (ICOS.4 mIgG2a). No toxicity wasapparent in any treatment group as demonstrated by mean and median bodyweight losses remaining below 20%.

Immuno-monitoring data indicated varying levels of intratumoral Tregdepletion in all anti-ICOS isotypes. In addition, elevated levels ofintratumoral CD8+ T cells were observed in all anti-mICOS.4 treatments.

Tumor responses were in part correlated with Treg reduction at Day 15,which agrees with the relative binding of these mAbs to Fc receptors.These data suggested that an anti-ICOS mAb that reduced Tregs would bemore potent than one that does not.

Antitumor Treatment

On Day 7 post implantation (2 Feb. 2015), 70 mice were randomized tofive groups of 14 mice according to tumor volume (L×W×H/2). Averagetumor volumes were approximately 134 mm³ for each group. On Days 7, 10,and 14, isotype control or the designated mAb was administered. Micewere dosed intraperitoneally (IP).

Immuno-Monitoring of T Cell Populations

To further study antitumor activity at the cellular level,immuno-monitoring was performed to look at subsets of immune cells intumor sites and to determine whether a link exists between antibodytreatment and changes in lymphoid cell populations. On Day 15, four micefrom each treatment group were harvested by the animal facility operatorfor tumors and spleens. The tissues were first processed on a gentleMACSOcto Dissociator™ (Miltenyi, San Diego, Calif.) and then stained fordifferent T cell markers. Samples were analyzed by flow cytometry on theFortessa cytometer (BD Biosciences, San Jose, Calif.).

Post-Treatment Monitoring

The mice's tumors and body weights were measured twice weekly throughstudy termination. Tumors were measured in three dimensions with anelectronic digital caliper, and data was electronically recorded usingStudyDirector software from Studylog Systems (South San Francisco,Calif.). Mice were checked daily for postural, grooming, and respiratorychanges, as well as lethargy. Mice were euthanized when the tumorsreached the 2000 mm³ endpoint or appeared ulcerated.

Results

Tumor Response

The last day all mice in the study were alive was Day 14 postimplantation, the last day of IP dosing. As a result, mean tumor growthinhibition (TGI) could not be calculated. On Day 23 post implantation,the last day when median TGI could be calculated, the treatment efficacyof the anti-ICOS isotypes on Sa1N tumors was evident when compared withisotype control treatment. Median TGI values were 21% (ICOS.1 mIgG1D265A), 55% (ICOS.4 mIgG1), 69% (ICOS.4 hIgG1), and 84% (ICOS.4 mIgG2a).

Tumor growth curves by treatment group are shown in FIGS. 12A-E. TGI issummarized by treatment group in Table 16. Mean and median tumor growthcurves by treatment group are presented in FIGS. 13A and 13B.

TABLE 16 Tumor Growth by Treatment Group Day 14 Day 23 Mean Median TumorTumor Volume TGI Volume TGI Treatment Group (mm³) (%) (mm³) (%) IsotypeControl mIgG1, 10 mg/kg 387 N/A 621 N/A Anti ICOS.1 mIgG1 D265A, 10mg/kg 295 24 493 21 Anti ICOS.4 mIgG1, 10 mg/kg 326 16 282 55 AntiICOS.4 hIgG1, 10 mg/kg 322 17 190 69 Anti ICOS.4 mIgG2a, 10 mg/kg 264 32101 84

The efficacy differences among the anti-ICOS isotypes demonstrated ahierarchy of mIgG2a>hIgG1>mIgG1>mIgG1 D265A. The inert mIgG1 D265Avariant, which cannot bind FcR, exhibited some antitumor activity with21% median TGI on Day 23. The unmodified mIgG1 isotype, which can engagethe inhibitory Fc receptor, FcγRIIB, may potentiate agonism and in thisstudy showed 55% median TGI on Day 23. Consistent with their higher TGIvalues, the mIgG2a and hIgG1 isotypes can bind murine activatingreceptors and mediate ADCC or antibody-dependent cellular phagocytosis(ADCP) of Tregs expressing ICOS. In addition, reduced levels ofintratumoral Tregs have been associated with increased tumor regressionin mouse tumor models. No toxicity was apparent in any treatment group,as the mean and median body weight changes were below 20%.

Changes in T Cell Populations

Treg depletion was observed at Day 15 in groups treated with mIgG2a andhIgG1 variants of the anti-ICOS.4 mAb since the percentages of Foxp3+cells were significantly lower in these groups than in the isotypecontrol group, as shown in FIGS. 14A-D. The same trend was also observedin the group treated with non-depleting anti-ICOS antibody (mIgG1). Inaddition, increased CD4+ effector T cells (Teffs) were evident in all ofthe treatment groups with the following ranking: mIgG1>hIgG1>mIgG2a.This observation suggested that some CD4+ Teffs, which are likely to beICOS+, may have been depleted by the mIgG2a isotype, which has thehighest depleting potential. Elevated levels of intratumoral CD8+ Tcells were also observed in all anti-mICOS.4 treatments.

Conclusion

As summarized in Table 17, in a staged Sa1N syngeneic tumor model,chimeric anti-ICOS isotypes promoted varying levels of antitumoractivity, ranging from 21% to 84% median TGI at Day 23. The antitumorpotencies of isotype variants in this study ranked as follows:mIgG2a>hIgG1>mIgG1>mIgG1 D265A. Tumor responses were in part correlatedwith Treg depletion at Day 15, which agrees with the relative binding ofthese mAbs to Fc receptors.

Results from this study showed that choice of isotype is an importantdeterminant of anti-ICOS antibody treatment. The anti-ICOS mIgG2aisotype, which binds activating Fcγ receptors equivalently to the humanIgG1 isotype, was able to deplete intratumoral Tregs and showed thegreatest efficacy in inhibiting tumor growth. Chimeric anti-ICOS isotypevariants promoted varying levels of antitumor activity. Tumor responseswere in part correlated with Treg depletion at Day 15, in agreement withthe relative binding of these mAbs to Fc receptors. Results suggestedmg2a promoted the best antitumor activity.

TABLE 17 In vivo Pharmacology Studies Schedule/Route/ Range of AnimalsType of Study/ Duration of Study/Vehicle/ Doses per group Species/StrainFormulation (μg/mouse) (M/F) Antitumor Antibodies administered IP on 10mg/kg 14 per activity of anti- post-implantation Days 7, 10, group; FICOS isotype and 14; variants in the Mouse IgG1 isotype control, Sa1Ntumor Anti-ICOS.1 mIgG1 D265A, model with Anti-ICOS.4 mIgG1,immunomonito Anti-ICOS.4 hIgG1, ring of immune Anti-ICOS.4 mIgG2a cellsubsets/ A/J mice

Example 8

Combination of Anti-ICOS Antibodies with an Anti-PD-1 Antibody

Study 1

To evaluate antitumor activity in the CT26 colorectal carcinoma modelafter treatment with an anti-ICOS surrogate monoclonal antibody, ICOS.4(mouse IgG1 variant of the parental hamster antibody), at varying dosesand/or anti-PD-1 mAb, CT26 cells were implanted subcutaneously in theright flanks of mice. When tumors reached 31 mm³, mice were randomizedinto nine treatment groups of 10 to 14 mice each. Each mouse was dosedon post-implantation Days 7, 10, and 14 with mAb or an isotype control(i.e., an antibody of the same isotype, but that does not bind anynaturally-occurring mouse protein, e.g., antibodies against KLH,diphtheria toxin, amongst others).

Mice were weighed and tumors were measured twice weekly through studytermination at Day 35. If tumors were ≥2000 mm³ or appeared ulcerated,animals were euthanized. On Day 15 after implantation, four mice in fourtreatment groups were sacrificed for spleen and tumor harvest. Tissueswere processed into single cell suspensions, and cells were stainedusing flow cytometry antibodies to analyze T cell populations.

On Day 21 post implantation, the last day when the mean tumor growthinhibition (TGI) relative to the isotype control antibody could becalculated, TGI values for anti-ICOS monotherapy were 37% and 33% at 3mg/kg and 10 mg/kg, respectively; TGI value for anti-PD-1 monotherapywas 22%. When anti-ICOS at 10 mg/kg, 3 mg/kg, or 1 mg/kg was combinedwith anti-PD-1 mAb, median TGI values>54% were observed. When anti-ICOSat 0.3, 0.1, or 0.03 mg/kg was combined with anti-PD-1 mAb, median TGIvalues<40 but >20% were observed. No toxicity was apparent in anytreatment group.

Antibody Treatment

On Day 7 post-CT26 cell implantation, 120 mice were randomized to 10groups of 10 to 14 mice each according to tumor volume. Groups had anaverage tumor volume of approximately 31 mm³. Mice were dosed with theantibodies on Days 7, 10, and 14.

Post-Treatment Monitoring

Mice were checked daily for postural, grooming, and respiratory changes,as well as lethargy. Animals were weighed at least twice weekly and wereeuthanized if weight loss was ≥20%. The flanks of each animal werechecked for the presence and size of tumors at least twice weekly untildeath, euthanasia, or end of the study period. Tumors were measured inthree dimensions (length [L], width [W], and height [H]) with electronicdigital calipers and recorded. Tumor volumes were calculated using theequation: Volume=(L×W×H×0.5). Response to treatment was measured as afunction of tumor growth inhibition (TGI) and was calculated as:(reference mm³−test article mm³)/reference mm³×100. When the tumorreached a volume greater than approximately 2000 mm³ or appearedulcerated, the animal was euthanized.

Immunomonitoring of T Cell Populations

To investigate the effect of ICOS antibody on T cell populations,tissues were harvested from four mice each in four treatment groups onDay 15 post-implantation. Spleens and tumors were homogenized on agentleMACS Octo Dissociator™ (Miltenyi, San Diego, Calif.). Single-cellsuspensions were stained for T cell markers usingfluorochrome-conjugated antibodies. Antibody fluorescence was detectedby flow cytometry on a Fortessa cytometer (BD Biosciences, San Jose,Calif.), and the results were analyzed using FlowJo software (FlowJo,LLC, Ashland, Oreg.).

Statistical Analysis

The mean, standard deviation (SD), and median values of tumor sizes andthe mean body weight values were calculated. The mean value wascalculated while 100% of study animals remained alive; and the medianvalue was calculated while at least 60% of study animals remained alive.One-way analysis of variance (ANOVA) was used to determine whether meansbetween treatment groups were statistically significantly different; pvalues≤0.05 were considered significantly different. GraphPad Prism®Version 5.01 software (GraphPad Software, La Jolla, Calif.) was used toplot data and determine statistical differences between groups. Tumorgrowth curves for individual mice by treatment group can be seen inFIGS. 15A-J. Mean and median tumor growth curves by treatment group arepresented in FIGS. 16A and 16B.

Results

Tumor Growth Inhibition

On Day 21 post tumor implantation, the last day when the median TGIcould be calculated, mice treated with anti-ICOS.4 mIgG1 as monotherapyat 10 mg/kg showed 33% median TGI relative to control mIgG1antibody-treated mice. Mice treated with anti-ICOS.4 mIgG1 monotherapyat 3 mg/kg showed 37% TGI and single-agent anti-PD-1 4H2 mAb showed 22%TGI. At the end of the study period (Day 35), proportions of tumor-freemice were 0/10 in the control antibody group, 0/10 in the anti-PD-1group, 1/10 in the anti-ICOS.4 mIgG1 group at 10 mg/kg, and 0/10 in theanti-ICOS.4 mIgG1 group at 3 mg/kg. The combination of anti-mouse PD-1with anti-ICOS.4 mIgG1 at various doses (10, 3, or 1 mg/kg) showedantitumor activity superior to that of either monotherapy (TGI values54%, 60%, and 66%, respectively). The numbers of tumor-free mice at theend of study were the same in these groups (1/10 tumor-free mice) withthe exception of the 3 mg/kg dose which had 4/10 tumor-free mice. Inaddition, median TGI was also calculated over the 21 days using therelative difference in the area under the effect curve between controland treatment groups (Table 18).

TABLE 18 Tumor Growth Inhibition by Treatment Group (Relative to IsotypeControl) Day 35 Day 21 Median Median Tumor Volume Median TGI TreatmentGroup Tumor Free Mice (mm³) TGI^(a) (over 21 days)^(b) 10 mg/kg mIgG1control mAb 0/10 558 — — 10 mg/kg anti-PD-1 4H2 mAb 0/10 433 22% 11% 10mg/kg anti-ICOS.4 mIgG1 mAb 0/10 376 33% 42% 3 mg/kg anti-ICOS.4 mIgG1mAb 0/10 349 37% 29% 10 mg/kg anti-ICOS.4 mIgG1 mAb + 1/10 256 54% 42%10 mg/kg anti-PD-1 4H2 mAb 3 mg/kg anti-ICOS.4 mIgG1 mAb + 4/10 222 60%44% 10 mg/kg anti-PD-1 4H2 mAb 1 mg/kg anti-ICOS.4 mIgG1 mAb + 1/10 19066% 48% 10 mg/kg anti-PD-1 4H2 mAb 0.3 mg/kg anti-ICOS.4 mIgG1 mAb +0/10 377 32% 14% 10 mg/kg anti-PD-1 4H2 mAb 0.1 mg/kg anti-ICOS.4 mIgG1mAb + 2/10 333 40% 28% 10 mg/kg anti-PD-1 4H2 mAb 0.03 mg/kg anti-ICOS.4mIgG1 mAb + 0/10 452 19% 21% 10 mg/kg anti-PD-1 4H2 mAb ^(a)% Median TGIwas calculated on Day 21 ^(b)% Median TGI (over 21 days) was calculatedusing the relative difference in the area under the effect curve betweencontrol and treatment group over 21 days

Immunomonitoring Analysis

Immunomonitoring was performed at Day 15 post-implantation in certaintreatment groups (FIGS. 17A-D). A depletion of Foxp3+ Tregs ontumor-infiltrating lymphocytes (TILs) was observed in the single-agentanti-ICOS.4 mIgG1 treated groups (10 mg/kg and 3 mg/kg) (FIG. 17A). Themice treated with anti-PD-1 mIgG1 did not show a reduction in TIL Tregs.The groups treated with anti-PD1 mIgG1 or anti-ICOS.4 at 3 mg/kg alsoshowed an increase in the CD8+ T cell subset in TILs (FIG. 17B). At 10mg/kg, the single-agent anti-ICOS.4 treatment seemed to have the similarlevels of this subset compared with the control group.

Levels of Ki-67, a marker for cell proliferation, were increased in theCD4+ effector T cell subset after single-agent treatment withanti-ICOS.4 mIgG1 at 3 mg/kg (FIG. 17C). The percent of cells positivefor granzyme B, a marker for cytolytic activity on CD8+ T cells, wasalso found to be higher in groups treated with either anti-ICOS mIgG1 at3 mg/kg or with anti-PD-1 alone (FIG. 17D).

Conclusion

In a staged CT26 syngeneic tumor model, anti-ICOS.4 mIgG1 as amonotherapy demonstrated more potent TGI when anti-ICOS.4 mIgG1 wasdosed at 3 mg/kg (37% TGI on Day 21, 0/10 tumor-free mice) vs. 10 mg/kg(33% TGI on Day 21, 0/10 tumor-free mice). Immunomonitoring data showeda higher percentage of CD8+ T cells, higher Ki-67 levels in CD4+effectors, and higher granzyme B levels in CD8+ T cells in the anti-ICOSmIgG1 3 mg/kg treatment group than in the 10 mg/kg treatment group.These data suggest that for anti-ICOS monotherapy, a 3 mg/kg dose hasmore antitumor activity than a 10 mg/kg dose.

The combination treatment of anti-ICOS.4 mIgG1 mAb at 10 mg/kg, 3 mg/kg,and 1 mg/kg, with anti-PD-1 mIgG1 resulted in median TGI values>54%,with 1/10 mice tumor free for these treatment groups, except anti-ICOS.4at 3 mg/kg, which had 4/10 mice tumor free. These results suggestcomparable levels of antitumor activity of the anti-ICOS mIgG1 incombination with anti-PD-1 mIgG1 treatments at the three highest doses.

Study 2

This study was designed to evaluate antitumor activity in the CT26colorectal carcinoma model after treatment with an anti-ICOS surrogatemonoclonal antibody, ICOS.4 (mouse IgG1 variant of the parental hamsterantibody) at varying doses and/or anti-PD-1 mAb. CT26 cells wereimplanted subcutaneously in the right flanks of mice. When tumorsreached 45 mm³, mice were randomized into nine treatment groups of 15 to20 mice each. Each mouse was dosed on post-implantation Days 9, 12, and15 with mAb or irrelevant isotype control. Mice were weighed and tumorswere measured twice weekly through study termination at Day 51. Iftumors were ≥2000 mm³ or appeared ulcerated, animals were euthanized.Whole blood samples were taken from mice at various time points (Day 9,Day 15, and Day 16 post-tumor implantation) for analysis. On Day 16after tumor implantation, five mice in eight treatment groups weresacrificed for spleen and tumor harvest. Tissues were processed intosingle cell suspensions, and cells were stained using flow cytometryantibodies to analyze T cell populations.

On Day 29 post-tumor implantation, the last day when the mean tumorgrowth inhibition (TGI) relative to the isotype control antibody couldbe calculated, TGI values for anti-ICOS monotherapy were 5% at 30 mg/kgand 33% at 3 mg/kg; anti-PD-1 monotherapy showed a TGI value of 74%.When anti-ICOS at 30 mg/kg, 10 mg/kg, 3 mg/kg, or 1 mg/kg was combinedwith anti-PD-1 mAb, mean TGI values>74% were observed. No toxicity wasapparent in any treatment group.

Antibody Treatment

On Day 9 post-tumor implantation, 200 mice were randomized to ninegroups of 15 to 20 mice each according to tumor volume. Groups had anaverage tumor volume of approximately 45 mm³. Mice were dosed with theantibodies on Days 9, 12, and 15.

Post-Treatment Monitoring

Animals were checked daily for postural, grooming, and respiratorychanges, as well as lethargy. Animals were weighed at least twice weeklyand were euthanized if weight loss was ≥20%. The flanks of each animalwere checked for the presence and size of tumors at least twice weeklyuntil death, euthanasia, or end of the study period. Tumors weremeasured in three dimensions (length [L], width [W], and height [H])with electronic digital calipers and recorded. Tumor volumes werecalculated using the equation: Volume=(L×W×H×0.5). Response to treatmentwas measured as a function of tumor growth inhibition (TGI) and wascalculated as: (reference mm³−test article mm³)/reference mm³×100. Whenthe tumor reached a volume greater than approximately 2000 mm³ orappeared ulcerated, the animal was euthanized.

Immunomonitoring of T Cell Populations

Various methods were used to investigate the effect of ICOS antibody onT and B cell populations. Whole blood samples were taken from mice atvarious time points (Day 9, Day 15, and Day 16) and then processed foranalysis. Additionally, tissues were harvested from five mice each ineight treatment groups on Day 16 post-implantation. Spleens and tumorswere homogenized on a gentleMACS Octo Dissociator™ (Miltenyi, San Diego,Calif.). Single-cell suspensions were stained for T cell markers usingthe fluorochrome-conjugated antibodies. Antibody fluorescence wasdetected by flow cytometry on a Fortessa cytometer (BD Biosciences, SanJose, Calif.), and the results were analyzed using FlowJo software(FlowJo, LLC, Ashland, Oreg.).

Statistical Analysis

The mean, standard deviation (SD), and median values of tumor sizes andthe mean body weight values were calculated. The mean value wascalculated while 100% of study animals remained alive; the median valuewas calculated while at least 60% of study animals remained alive.One-way analysis of variance (ANOVA) was used to determine whether meansbetween treatment groups were statistically significantly different; pvalues≤0.05 were considered significantly different. GraphPad Prism®Version 7.02 software (GraphPad Software, La Jolla, Calif.) was used toplot data and determine statistical differences between groups. Tumorgrowth curves for individual mice by treatment group can be seen inFIGS. 18A-I. Mean and median tumor growth curves by treatment group arepresented in FIGS. 19A and 19B.

Results

Tumor Growth Inhibition

At Day 29 post-tumor implantation, the last day the mean TGI could becalculated, the treatment efficacy of the anti-ICOS mAb therapies onCT26 tumors was observed as both monotherapy and in combination withanti-PD-1 mAb (Table 19). Mice treated with anti-ICOS.4 mIgG1monotherapy at 3 mg/kg showed 33% TGI and single-agent anti-PD-1 4H2 mAbshowed 74% TGI. At the end of the study period (Day 51), the number oftumor-free mice were 0/10 in the control antibody group, 8/15 in theanti-PD-1 group, and 1/15 across all anti-ICOS.4 mIgG1 doses (30 mg/kg,10 mg/kg, or 3 mg/kg). The combination of anti-PD-1 with anti-ICOS.4mIgG1 at various doses (30 mg/kg, 10 mg/kg, 3 mg/kg, and 1 mg/kg) showedantitumor activity superior or equal to that of the monotherapy (TGIvalues 74%, 80%, 87%, and 78% respectively). The number of tumor-freemice at the end of study ranged from 8-11/15 across the four combinationgroups.

TABLE 19 Tumor Growth Inhibition by Treatment Group (Relative to IsotypeControl) Day 29 Mean Tumor Mean Treatment Group Volume (mm³) % TGI 30mg/kg mIgG1 control mAb 1248 N/A 5 mg/kg anti-PD-1 4H2 mAb 327 74% 30mg/kg anti-ICOS.4 mIgG1 mAb 1182  5% 10 mg/kg anti-ICOS.4 mIgG1 mAb N/AN/A 3 mg/kg anti-ICOS.4 mIgG1 mAb 838 33% 30 mg/kg anti-ICOS.4 mIgG1mAb + 328 74% 5 mg/kg anti-PD-1 4H2 mAb 10 mg/kg anti-ICOS.4 mIgG1 mAb +252 80% 5 mg/kg anti-PD-1 4H2 mAb 3 mg/kg anti-ICOS.4 mIgG1 mAb + 15887% 5 mg/kg anti-PD-1 4H2 mAb 1 mg/kg anti-ICOS.4 mIgG1 mAb + 271 78% 5mg/kg anti-PD-1 4H2 mAb

Immunomonitoring Analysis

Immunomonitoring was performed at various time points post-implantationin certain treatment groups (FIGS. 20A-D). On Day 16 post-tumorimplantation, a depletion of FoxP3+ Tregs on tumor-infiltratinglymphocytes (TILs) was observed in all groups treated with anti-ICOS.4mIgG1 mAb (FIGS. 20A and 20B). The CT26 tumor-bearing mice treated withanti-PD-1 mIgG1 alone did not show a reduction in TIL Tregs. Althoughmore variable, CD8+ T cells increased on TILs in all treatment groupsversus control (FIG. 20D).

Levels of Ki-67 protein, a marker for cell proliferation, increased inthe CD4+ effector T cell subset after single-agent treatment with eitheranti-PD-1 (moderate increase) or anti-ICOS.4 mIgG1 (high increase)(FIGS. 21A-C). Further increase in Ki-67 levels were observed in theanti-PD-1 and anti-ICOS.4 mIgG1 combination treatment groups.

ICOS-L, the ligand for ICOS, showed higher mean fluorescence intensity(MFI) levels on B cells after treatment with anti-ICOS.4 antibodies. MFIlevels of ICOS-L were also elevated in whole blood taken at Day 9, Day15, and Day 16 post-tumor implantation, and in spleen on Day 16post-tumor implantation. A trend seems to emerge where the highest doseof anti-ICOS.4 mIgG1 has the highest MFI for ICOS-L (FIGS. 22A-D).

Looking at ICOS levels, loss of receptor expression on CD4+ T cells wasobserved after antibody treatment. This was most apparent in the tumorTILS (Table 20). Higher doses of anti-ICOS.4 mIgG1 correlated with lowerlevels of ICOS. Dosing of antibodies (Isotype Control at 30 mg/kg andAnti-PD-1 mIgG1 D265A at 5 mg/kg; Anti-ICOS.4 mIgG1 mAb at 1 mg/kg, 3mg/kg, 10 mg/kg, and 30 mg/kg dose levels) was by intraperitonealinjection on days 9, 12, and 15 post-CT26 cell implantation. Whole bloodwas collected at various timepoints (day 9, day 15 and day 16 postimplantation), and tumor was harvested on day 16 post implantation fromfive mice in certain treatment groups. Immuno-monitoring analysis viaflow cytometry was performed on processed samples.

TABLE 20 Expression of ICOS on CD4+ T Cells mIgG1 ICOS.4 mIgG1 TissueDay post- (30 mpk) [% ICOS] analyzed implantation [% ICOS] 30 mpk 10 mpk3 mpk PBMC 9 100% 67% 75% 86% PBMC 15 100% 65% 50% 65% PBMC 16 100% —43% 50% Tumor 16 100% — 18% 15%

Conclusions

As summarized in Table 21, in a staged CT26 syngeneic tumor model,treatment with anti-ICOS.4 mIgG1 mAb showed antitumor activity both as asingle agent or when combined with anti-PD-1 mAb. As a monotherapy,similar levels of anti-tumor activity were observed when anti-ICOS.4mIgG1 was dosed at 30 mg/kg, 10 mg/kg, or 3 mg/kg, although the 3 mg/kgdose had the highest mean TGI (33%) on Day 29. Immunomonitoring datashowed an increased depletion of FoxP3+ Tregs (tumor), higher percentageof CD8+ T cells (tumor), higher Ki-67 protein levels in CD4+ effectors(tumor), higher ICOS-L levels in B cells (whole blood and spleen), andloss of ICOS expression in CD4+ T cells (whole blood and spleen) withacross all doses of groups treated with anti-ICOS.4 mIgG1. These datashowed that anti-ICOS monotherapy has good efficacy in this tumor model.

Anti-PD-1 mIgG1 treatment had very strong activity in this experiment.The combination treatment of anti-ICOS.4 mIgG1 mAb at 30 mg/kg, 10mg/kg, 3 mg/kg, and 1 mg/kg, with anti-PD-1 mIgG1 resulted in mean TGIvalues≥74%, with 8-11/15 mice tumor free for these treatment groups.These results showed comparable levels of antitumor activity of theanti-ICOS mIgG1 in combination with anti-PD-1 mIgG1 treatments acrossall doses. Improved antitumor efficacy in the CT26 model was observedwhen combining anti-ICOS and anti-PD-1 mAb. Tumor growth inhibition was≥74% for each of the four doses (1 mg/kg, 3 mg/kg, 10 mg/kg, 30 mg/kg)anti-ICOS treatment groups in combination with anti-PD-1, with at least8/15 mice tumor free in each of these groups. Tumor growth inhibition ofanti-ICOS mAb as a single agent was 33% with 1/15 mice tumor free whendosed at 3 mg/kg. Immunomonitoring also showed lower FoxP3+ Tregs,higher percentages of CD8+ T cells, higher Ki-67 levels in CD4+effectors, higher ICOS-L levels in B cells, and lower ICOS receptorexpression levels in the anti-ICOS monotherapy.

TABLE 21 In vivo Nonclinical Pharmacology StudiesSchedule/Route/Duration of Study/ Range of Animals Type of Study/Vehicle/ Doses per group Species/Strain Formulation (μg/mouse) (M/F)Antitumor Antibodies administered IP on 1-30 mg/kg 15-20 per activity ofanti- post-implantation Days 9, 12, and 15; group; F ICOS mAb in MouseIgG1 isotype control, combination Anti-ICOS.4 mIgG1, with anti-PD-1Anti-PD-1 clone 4H2 mIgG1 mAb in the CT26 tumor model withimmunomonitoring of immune cell subsets/ Balb/c mice

Example 9 Antitumor Activity of Anti-ICOS Antibody in Combination withAnti-CTLA-4 in a CT26 Tumor Model

Summary

To evaluate antitumor activity in the CT26 colorectal carcinoma modelafter treatment with an anti-ICOS surrogate monoclonal antibody ofvarying Fcs, ICOS.4 (mouse IgG1 or IgG2 variant of the parental hamsterantibody), and/or anti-CTLA-4 mAb, CT26 cells were implantedsubcutaneously in the right flanks of mice. When tumors reached 96 mm³,mice were randomized into six treatment groups of 10 to 15 mice each.Each mouse was dosed on post-implantation Days 13, 16, and 20 with mAbor isotype control (i.e., antibody of the same isotype, but that doesnot bind any naturally-occurring mouse protein, e.g., antibodies againstKLH, diphtheria toxin, amongst others). Mice were weighed and tumorswere measured twice weekly through study termination at Day 66. Iftumors were ≥2000 mm³ or appeared ulcerated, animals were euthanized.

On Day 30 post implantation, the last day when the median tumor growthinhibition (TGI) relative to the isotype control antibody could becalculated, TGI values for anti-ICOS monotherapy were 15% and 69% withmIgG1 and mIgG2a variants (e.g., chimeric mouse antibody withV_(H)/V_(L) sequences SEQ ID NOs: 3 and 4+IgG1 or IgG2), respectively;anti-CTLA-4 monotherapy showed a TGI value of −7%. When anti-ICOS mAbswere combined with anti-CTLA-4 mAb, mean TGI values of 40% (mIgG1) and79% (mIgG2a) were observed. No toxicity was apparent in any treatmentgroup.

EXPERIMENTAL PROCEDURES

Test Antibodies and Controls

The following antibodies were constructed:

(a) Anti-Mouse ICOS Mouse IgG1 Antibody—Anti-ICOS.4 mAb, isotype mouseIgG1, was expressed from Chinese hamster ovary (CHO) cell lines;

(b) Anti-Mouse ICOS Mouse IgG2a Antibody—Anti-ICOS.4 mAb, isotype mouseIgG2a, was expressed from CHO cell lines;

(c) Anti-Mouse CTLA-4 9D9 Mouse IgG2b Antibody—Monoclonal antibody tomouse CTLA-4 clone 9D9, isotype mouse IgG2b, was expressed from atransfected CHO cell line and formulated in PBS; and

(d) Mouse IgG1 Isotype Control—A fully murine IgG1 antibody, non-bindingto ICOS; prepared at 10 mg/kg in PBS.

Preparation of Tumor Cells

CT26 murine colon carcinoma cells were purchased from American TypeCulture Collection (ATCC, Catalog CRL-2638) and maintained in vitro insterile culture of Dulbecco's modified eagle medium (DMEM)+10%heat-inactivated fetal bovine serum (FBS), for less than 10 passages.Cells were confirmed to be virus-free via mouse antibody productiontesting.

Tumor Implantation

CT26 cells were cultured in RPMI-1640 medium (HyClone/GE Healthcare,Logan Utah, Catalog 10-040-CM, Lot 16915003) supplemented with 10% fetalbovine serum (FBS) (Gibco, Life Technologies, Catalog 26140-079, Lot1704315). Cells were split 1:10 every three to four days. The rightflank of each mouse was subcutaneously implanted with 1×10⁶ CT26 cellsin 0.2 mL PBS using a 1-cm syringe and a 26-gauge half-inch needle.

Antibody Treatment

On Day 13 post-CT26 cell implantation, 120 mice were randomized to sixgroups of 10 to 15 mice each according to tumor volume. Groups had anaverage tumor volume of approximately 96 mm³. Mice were dosed with theantibodies on Days 13, 16, and 20.

Post-Treatment Monitoring

Animals were checked daily for postural, grooming, and respiratorychanges, as well as lethargy. Animals were weighed at least twice weeklyand were euthanized if weight loss was greater than or equal to 20%. Theflanks of each animal were checked for the presence and size of tumorsat least twice weekly until death, euthanasia, or end of the studyperiod. Tumors were measured in three dimensions (length [L], width [W],and height [H]) with electronic digital calipers and recorded. Tumorvolumes were calculated using the equation: Volume=(L×W×H×0.5). Responseto treatment was measured as a function of tumor growth inhibition (TGI)and was calculated as: (reference mm³−test article mm³)/referencemm³×100. When the tumor reached a volume greater than approximately 2000mm³ or appeared ulcerated, the animal was euthanized.

Results

As shown in Table 22, at Day 30 post-tumor implantation, the last daythe median TGI could be calculated, the treatment efficacy of theanti-ICOS mAb therapies on CT26 tumors was observed as both monotherapyand in combination with anti-CTLA-4 mAb. Mice treated with anti-ICOS.4variants as monotherapy showed 15% median TGI (mIgG1) and 69% TGI(mIgG2a). The combination of anti-CTLA-4 mAb (−7% TGI), resulted inhigher median TGIs as the anti-ICOS.4 mIgG1 variant had 40% TGI, and theanti-ICOS.4 mg2a variant had 79% TGI. At the end of the study period(Day 66), the number of tumor-free mice was 0 for all groups. Tumorgrowth curves for individual mice by treatment group are shown in FIGS.23A-F. Dosing of antibodies (isotype control at 20 mg/kg; anti-CTLA-4mIgG2b, anti-ICOS.4 mIgG1, and anti-ICOS.4 mIgG2a at 10 mg/kg) was byintraperitoneal injection on days 13, 16, and 20 post-CT26 cellimplantation.

Mean and median tumor growth curves by treatment group are presented inFIGS. 24A and 24B. No toxicity was apparent in any treatment group, asthe mean and median body weight changes were below 20%.

TABLE 22 Tumor Growth Inhibition by Treatment Group Day 30 Median TumorMedian Treatment Group Volume (mm³) % TGI mIgG1 isotype control, 20mg/kg 1981 N/A Anti-ICOS.4 mIgG1, 10 mg/kg 1686 15% Anti-ICOS.4 mIgG2a,10 mg/kg 614 69% Anti-CTLA-4 9D9 mIgG2b, 10 mg/kg 2114 −7% Anti-ICOS.4mIgG1, 10 mg/kg + Anti-CTLA-4 1195 40% 9D9 mIgG2b, 10 mg/kg Anti-ICOS.4mIgG2a, 10 mg/kg + 410 79% Anti-CTLA-4 9D9 mIgG2b, 10 mg/kg

Conclusions

As summarized in Table 23, in a staged CT26 syngeneic tumor model, bothanti-ICOS Fc variant monotherapies (i.e., ICOS.4 mouse IgG1 or IgG2variant of the parental hamster antibody) promoted modest antitumoractivity, with anti-ICOS.4 mIgG2a demonstrating greater efficacy thananti-ICOS.4 mIgG1 at Day 30 (69% versus 15% median TGI). The combinationof the anti-ICOS.4 treatments with anti-CTLA-4 mAb increased efficacywith the median TGIs increasing to 79% (mIgG2a) and 40% (mIgG1). Nosignificant changes in body weight were associated with the treatmentsnor were any overt signs of clinical toxicity observed. Anti-ICOSmonotherapies promoted antitumor activity, with anti-ICOS.4 mIgG2ademonstrating greater antitumor efficacy at Day 30 (69% versus 15%median TGI). Antitumor efficacy increased when combined with anti-CTLA-4mAb treatment, with anti-ICOS.4 mIgG2a combination group at 79% TGI andanti-ICOS.4 mIgG1 at 40% TGI.

TABLE 23 In vivo Pharmacology Studies Schedule/Route/ Range of AnimalsType of Study/ Duration of Study/Vehicle/ Doses per group Species/StrainFormulation (μg/mouse) (M/F) Antitumor Antibodies administered IP on10-20 mg/kg 10-15 per activity of anti- post-implantation Days 13,group; F ICOS mAb in 16, and 20; (female) combination 66 days; withanti- Mouse IgG1 isotype control, CTLA-4 mAb Anti-ICOS.4 mIgG1, in theCT26 Anti-ICOS.4 mIgG2a, tumor model/ Anti-CTLA-4 9D9 mIgG2b, Balb/cmice in PBS

Example 10 Affinity, Binding, Biophysical Properties, Forced Stability,and Immunogenicity

Characterization of Binding Properties

Human CD4+ T cells, cynomolgus PBMC and mouse and rat splenocytes wereactivated by incubation with plate-bound species-specific anti-CD3(coated in a 6-well plate with 2 mL/well of a 4 μg/mL solution in PBSfor 3 hours at 37° C. and washed twice with 1 mL medium), +1 μg/mLsoluble species-specific anti-CD28 in fresh medium with 1-2×10⁶ cells/mLfor 3-4 days. It should be noted that the cynomolgus PBMC and mouse andrat splenocytes become primarily T cells after three to four days ofCD3/CD28 activation. The cells were harvested, counted, spun down andre-suspended in staining buffer+100 μg/mL mouse IgG to block for 15minutes at room temperature. ICOS.33 IgG1f S267E was titrated from 2μg/mL by 4-fold serial dilutions down to 0.002 μg/mL in staining bufferand incubated with the activated human, cynomolgus monkey, rat or mousecells for 30 minutes at 4-8° C. in a U-bottom plate. The cells were thenwashed twice in 150-200 μL of staining wash buffer and re-suspended in50 μL of APC-Goat Anti-Human IgG (Fc gamma) diluted 1:200 in stainingbuffer, gently vortexed, and incubated 30 minutes at 4-8° C. in thedark. The cells were then washed once in 200 μL staining wash buffer,re-suspended in same and analyzed on the FACS Canto flow cytometer.

As illustrated in FIGS. 25A and 25B, ICOS.33 IgG1f S267E exhibits strongbinding to human, cynomolgus monkey, rat and mouse T cells with EC50values that are not significantly different among the three species.

In addition, the binding avidity of ICOS.33 IgG1f S257E was compared totwo different anti-ICOS competitor antibodies. Briefly, the antibodieswere incubated with activated CD4+ T cells on ice for thirty minutes.The cells were then washed, and the bound antibodies were detected withan anti-human-IgG-PE secondary reagent. The signal was measured by flowcytometry, and the mean fluorescence intensity was calculated. As shownin FIGS. 26A-B, ICOS.33 IgG1f S267E showed greater binding avidity toactivated CD4+ T cells as calculated by EC50 compared to the twocompetitor antibodies. As discussed herein, the term “EC50”, in thecontext of an in vitro assay using an antibody or antigen bindingfragment thereof, refers to the concentration of an antibody or anantigen-binding fragment thereof that induces a response that is 50% ofthe maximal response, i.e., halfway between the maximal response and thebaseline. In FIG. 26A, the EC50 of ICOS.33 IgG1f S267E was about 0.07μg/mL, whereas the EC50 of competitor antibody 1 was about 1.4 μg/mL,and the EC50 of competitor antibody 2 was about 0.4 μg/mL. In otherwords, the EC50 of ICOS.33 IgG1f S267E was about 20-fold less than theEC50 of competitor antibody 1, and about 6-fold less than the EC50 forcompetitor antibody 2. In FIG. 26B, the EC50 of ICOS.33 IgG1f S267E wasabout 0.08 μg/mL, whereas the EC50 of competitor antibody 1 was about2.4 g/mL, and the EC50 of competitor antibody 2 was about 1.0 μg/mL. Inother words, the EC50 of ICOS.33 IgG1f S267E was about 30-fold less thanthe EC50 of competitor antibody 1, and about 12-fold less than the EC50for competitor antibody 2.

Affinity Studies

Since monomeric human ICOS was not available, experiments to determinethe true affinity of ICOS.33 IgG1f S267E were done using ICOS.33 IgG1fS267E Fab fragment (Lot PC-1804-04) and human ICOS Fc (R&D Systems,169-CS-050) antigen with Biacore™ T200 equipment. The bindingexperiments were done at 37° C. to obtain (or model) the affinity of theantibody to the antigen under in vivo conditions. A CM4 chip wascovalently coated with anti-hFc capture reagent from Biacore. Thesurface was blocked with ethylenediamine. Next, human ICOS with an Fctag was captured on the CM4 chip and the Fab fragment of ICOS.33 IgG1fS267E was flowed on it at 0.91, 2.7, 25, 74, 667, and 2000 nMconcentrations.

The association rate constant (kon) and disassociation rate constant(koff) were plotted by time and response units (RU) using BIAevaluationsoftware, Version 3.2. The data were fit to a 1:1 Langmuir model. Theratio of koff/kon was represented by the dissociation constant (K_(D))of the antibody-antigen complex. The Biacore chip was regenerated with50 mM sodium hydroxide solution at a flow rate of 100 μL/min. Theaffinity of the antibody for the human ICOS antigen as measured by Fabfragment of ICOS.33 IgG1f S267E was 52 nM to 65 nM.

Biophysical Analysis

The identity of ICOS.33 IgG1f S267E was confirmed by liquidchromatography/mass spectrometry (LC-MS). For heavy and light chain massmeasurements, the sample was deglycosylated, reduced, and alkylated perthe standard test method and analyzed using a Waters LCT Premier ESI-TOFinstrument. The mass of ICOS.33 IgG1f S267E light and heavy chains wereequivalent to their predicted mass assignments of 23,795 Da and 50,161Da, respectively, based on amino acid sequence derived from DNAsequence.

The identity of the antibody was determined by Edman sequence analysis.N-terminal amino acid sequencing of antibody heavy and light chains wasperformed with an ABI Procise Automated Protein Sequence Analyzer. Theobserved N-terminal amino acid sequences of ICOS.33 IgG1f S267E matchedthe predicted amino acid sequences for the light and heavy chains.

Using the Agilent 2100 BioAnalyzer system, it was determined thatICOS.33 IgG1f S267E migrated at approximately 160 kDa under non-reducing(NR) conditions. Under reducing conditions (R), the heavy chain migratedat about 60 kDa and the light chain migrated at about 25 kDa.

The purity of ICOS.33 IgG1f S267E was determined by capillaryelectrophoresis-sodium dodecyl sulfate (CE-SDS). Samples were analyzedwith a Beckman Coulter Proteome Lab PA 800 plus under non-reducing andreducing conditions. ICOS.33 IgG1f S267E comprised 93.45% intact IgG byCE-SDS under non-reducing conditions. The antibody fragments detectedwere as follows: a light chain (1.85%), a heavy-light chain (0.45%), twoheavy chains (0.88%) and two heavy and one light chain (3.37%). Thepurity of ICOS.33 IgG1f S267E was 96.51% (62.22% heavy chain+34.29%light chain) by CE-SDS under reducing conditions.

ICOS.33 IgG1f S267E was characterized by hydrophobic interactionchromatography (HIC) to determine the level of product heterogeneity.ICOS.33 IgG1f S267E showed low heterogeneity with 98.1% main peak, 0.4%peak in front of the main peak, and 1.5% tailing shoulder, indicatinglow chemical or conformational heterogeneity.

Capillary isoelectric focusing (cIEF) was utilized to characterizeICOS.33 IgG1f S267E for charge isoforms. The sample was analyzed usingan iCE Analyzer Model iCE3. ICOS.33 IgG1f S267E displayed an isoelectricpoint (pI) range of 7.30 to 7.72 with a major peak at 7.72 (45.19%).Other peaks observed were at 7.30 (7.51%), 7.40 (16.21%) and 7.56(31.10%). The observed pI range was within the normal range expected forIgG1 antibody samples.

Size-exclusion chromatography (SEC; gel filtration) coupled withmulti-angle light scattering (MALS) was performed to determine themonomer content and MW distribution of the major impurities of ICOS.33IgG1f S267E. It was found that ICOS.33 IgG1f S267E comprised more than99.8% monomer. The MW assignment by MALS indicated that the monomericcomponent had a MW of 144,300 Da. A very small amount of aggregate hadan apparent MW of 626,800 Da.

Peptide fingerprinting and sequencing was performed by analyzingdigested peptides by LC-MS on a Waters Acquity UPLC with an Acquity UPLCBEH C18 1.7 μm (2.1×150 mm; Waters Corporation) coupled to anLTQ-Orbitrap XL mass spectrometer. The heavy and light chain sequenceidentification was 100% using the MS/MS data from various digestsincluding trypsin, chymotrypsin, and pepsin. Peptide sequencingconfirmed that the allotype was human IgG1 and matched the expectedamino acid sequence as predicted by the DNA sequence. A singleN-glycosylation site was confirmed to be N297 on the heavy chain. Thedisulfide bonds were found to be as expected for a human IgG1 monoclonalantibody. The S267E mutation made to enhance the CD32b receptor bindingwas also identified in the sequence.

The oligosaccharide profile of N-linked sugars present on ICOS.33 IgG1fS267E was determined by capillary laser-induced fluorescence (cLIF)using a Beckman MDQ instrument. N-linked glycans present on ICOS.33IgG1f S267E comprised a mixture of asialo-biantennary sugars withoutfucose that varied with respect to the level of galactose incorporation.The major glycan structures were GOF (30.64%) and G1F (43.65%), and to alesser degree, G2F (19.07%).

A VP-capillary differential scanning calorimeter was used to determinethermal stability and reversibility of the antibody. Data were analyzedusing the Origin 7 software program. Thermal stability was withinacceptable range for a typical human monoclonal antibody. In thermalscanning experiments, many antibodies show three resolvable meltingtemperatures; the first one is due to the unfolding of CH2 domain, thesecond is due to the unfolding of the Fab domain, and the third is dueto the unfolding of CH3 domain. ICOS.33 IgG1f S267E displayed athermogram with these three unfolding temperatures: 65.2° C. (Tm1),83.2° C. (Tm2), 86.3° C. (Tm3). Thermal reversibility is a marker forthe ability of a protein to refold back to its native conformation aftera perturbation, in this case heat. Thermal reversibility experiments at83.2° C. (the second melting temperature) showed 55.2% reversibility,which suggests that the antibody has robust refolding properties.

The stability of ICOS.33 IgG1f S267E is summarized in Table 24.

TABLE 24 Stability of ICOS.33 IgG1f S267E Property Method ResultsFreeze/Thaw (1 h at −80° C., 1 h UV, SEC No F/T stability risk revealedat RT × 6) Solubility/Concentration UV, SEC At least 50 mg/ml in buffer(20 mM Profile histidine, pH 6.0, 260 mM sucrose) Agitation StabilityStudy 350 rpm at RT in buffer (20 mM No aggregation issues observedhistidine, pH 6.0, 260 mM sucrose) +/− 0.05% PS80 for 7 days (50 and 10mg/mL)

Example 11 ICOS.33 IgG1f S267E Binding Affinity for Human FcγRs bySurface Plasmon Resonance

The binding of human FcγRs to ICOS.33 IgG1f S267E was studied by surfaceplasmon resonance (SPR) and compared to control antibody anti-ICOSIgG1f. Antibodies were captured on a protein A sensor surface, and atitration series of FcγRs were injected as analytes.

For these studies, protein A was immobilized on flow cells 1-4 of theCM5 sensor chip using standard ethyl (dimethylaminopropyl) carbodiimide(EDC)/N-hydroxysuccinimide (NHS) chemistry, with ethanolamine blocking,in a running buffer of 10 mM HEPES pH 7.4, 150 mM NaCl, 3 mM EDTA, 0.05%surfactant p20, to a density of ˜3000 RU. ICOS.33 IgG1f S267E (3 μg/mL)or hIgG1f control antibody (3 μg/mL) were captured on the protein Asurface to a density of ˜400-500 RU, and the binding of FcγR analyteswas tested in running buffer consisting of 10 mM NaPO4, 130 mM NaCl,0.05% p20, buffer (PBS-T) pH 7.1 at 25° C., using 120 second associationtime and 180 second dissociation time at a flow rate of 30 μL/min. Todetermine the kinetics and affinity of binding, an FcγR concentrationseries (3:1 dilution) from 1 μM down to 0.15 nM (CD64 proteins) or 10 μMdown to 1.5 nM (all other FcγRs) was tested. The kinetic data were fitto either a 1:1 Langmuir model or to a steady-state model using BiacoreT200 evaluation software.

Sensorgram data that demonstrated very rapid association anddissociation rates with steady-state binding were fit to a 1:1 steadystate affinity model, while those that demonstrated slower kinetics werefit to a 1:1 Langmuir model. Data at single analyte concentrations(hCD64 at 0.11 μM and hCD32a-H131, hCD32a-R131, hCD32b, hCD16a-V158,hCD16a-F158, hCD16b-NA1, and hCD16b-NA21.at 1.1 μM) were compared foranti-ICOS control antibody and ICOS.33 IgG1f S267E, with ICOS.33 IgG1fS267E showing a higher binding response and slower dissociation rate forseveral of the FcγRs, with hCD32a-R131 and hCD32b having the mostnotable increases in binding and slower dissociation rates.

The best fit kinetic and affinity values are shown in Table 25. Thesedata quantitatively demonstrated that the S267E mutation changes thebinding affinity for several FcRs compared to hIgG1f control antibody.For example, binding to hCD32a-R131 improved from a K_(D) of 1500 nM(hIgG1f control) to 34 nM (ICOS.33 IgG1f S267E), which was animprovement of more than 40-fold, and binding to hCD32b improved from aK_(D) of greater than 5000 nM (hIgG1f control) to 170 nM (ICOS.33 IgG1fS267E), which was an improvement of at least 29-fold. Binding to cynoCD32a and CD32b was lower than that seen for human CD32a and CD32b.

TABLE 25 Kinetic and Affinity Data for the Binding of ICOS.33 IgG1fS267E to Human FcγRs Ligand FcγRs ka (1/Ms) kd (1/s) K_(D) (nM) ModelAnti-ICOS Control hCD64 1.1 × 10⁶ 6.0 × 10⁻⁵ 0.1 1:1 Langmuir FitAntibody hCD32a-H131 1100 Steady State Affinity hCD32a-R131 1500 SteadyState Affinity hCD32b >5000 Steady State Affinity hCD16a-V158 560 SteadyState Affinity hCD16a-F158 >5000 Steady State Affinity hCD16B-NA1 3500Steady State Affinity hCD16B-NA2 >5000 Steady State Affinity ICOS.33hCD64 1.6 × 10⁶ 5.1 × 10⁻⁵ 0.03 1:1 Langmuir Fit IgG1fS267E hCD32a-H131840 Steady State Affinity hCD32a-R131 34 Steady State Affinity hCD32b170 Steady State Affinity hCD16a-V158 1400 Steady State AffinityhCD16a-F158 >5000 Steady State Affinity hCD16B-NA1 1400 Steady StateAffinity hCD16B-NA2 >5000 Steady State Affinity cyCD64 .88 1:1 LangmuirFit cyCD32a 4000 Steady State Affinity cyCD32b 2300 Steady StateAffinity cyCD16 1700 Steady State Affinity

Example 12 Pharmacokinetics (PK) of ICOS.33 IgG1f S267E

The PK parameters obtained from a single-dose PK/PD and tolerabilitystudy with ICOS.33 IgG1f S267E are summarized in Table 26. The exposurewas dose-proportional between 1 mg/kg and 10 mg/kg, with a half-life of13-14 days. Anti-drug antibodies (ADA) were detected at seven days postdose in three out of four cynomolgus monkeys in the 1 mg/kg dose groupand continued to increase up to 42 days post dose. The increase in theADA signal corresponded with the rapid clearance of the antibody inthese monkeys, and this portion of the data affected by ADA were notincluded in the PK data analysis.

TABLE 26 Pharmacokinetic Parameters of ICOS.33 IgG1f S267E afterIntravenous (IV) Administration to Cynomolgus Monkeys Area Under Volumeat the Curve T½ Clearance steady state Monkey Dose (AUC)(0-INF)(half-life) (CLT) (Vss) Study number (mg/kg) (μM × d) (days) (mL/d/kg)(mL/kg) DT15107 4 (2 Female/ 1 2.2 ± 0.4 13 ± 2.8 3.1 ± 0.46 57 ± 3.9 2Male) 4 (2 Female/ 10  23 ± 3.8 14 ± 3.3 2.9 ± 0.48 66 ± 11  2 Male)

Pharmacokinetics of Mouse Surrogate Antibody in Mice

The pharmacokinetics of an anti-mouse ICOS surrogate mAb (ICOS.4, mouseIgG1 variant of the parental hamster antibody) following a singleintravenous dose at 1 mg/kg and a single intraperitoneal administration(at 0.1 mg/kg, 1 mg/kg, and 10 mg/kg) were evaluated innon-tumor-bearing BALB/c mice, which is an albino, laboratory-bredstrain of the house mouse. The antibody showed agreater-than-dose-proportional increase in exposure over a 1 mg/kg-10mg/kg dose range, as shown in Table 27. The half-life ranged from 0.53days at the lowest 1 mg/kg dose to 1.5 days at the highest 10 mg/g dose.The nonlinear PK in mice appeared to be due at least in part totarget-mediated drug disposition.

TABLE 27 Pharmacokinetics Parameters of ICOS.4 mouse IgG1 afterIntraperitoneal Administration to Mice Route of adminis- Dose CmaxAUC(0-INF) T½ CLT Vss tration (mg/kg)| (nM) (μM × d) (d) (mL/d/kg)(mL/kg) IV 1 0.15 0.65 43.2 101.4 IP 0.1 4.1 0.005 0.55 IP 1 51 0.1870.53 IP 10 703 3.3 1.5

Example 13 Cross-Reactivity and Tissue Staining

Binding assays have demonstrated that ICOS.33 IgG1f S267E affinity(EC50) to activated CD4+ T cells was similar in mice, rats, cynomolgusmonkeys, and humans.

In tissue cross-reactivity analysis, FITC-conjugated ICOS.33 IgG1f S267Ewas applied to frozen sections (acetone or acetone/formalin fixed) from20 normal human tissues, one to four donors each. Specific staining wasobserved in subsets of lymphocytes in lymphoid (thymus, tonsil, andspleen) and lymphoid-rich tissues (stomach and small intestine), as wellas scattered very rare mononuclear cells (MNCs) in several tissues(thyroid, skin, lung, uterus, and testis), which are largely associatedwith underlying inflammation. No positive labeling was seen in cerebrum,cerebellum, heart, liver, kidney, pancreas, peripheral nerve, colon,pituitary, and prostate. In lymphoid tissues, positive lymphocytes wereprimarily distributed in the medulla of the thymus, and the light zoneof the germinal center and interfollicular region of the tonsil. Theseresults are consistent with previous immunohistochemistry (IHC) with theparent antibody ICOS.4.

ICOS.33 IgG1f S267E-FITC staining was also evaluated byimmunohistochemistry (IHC) in frozen sections from 10 normal cynomolgusmonkey tissues, including cerebrum, heart, liver, lung, kidney, spleen,thymus, tonsil, skin, and testis. Overall, the staining patterns weresimilar to that in human tissues. Specific staining was observed insubsets of lymphocytes in lymphoid tissues (tonsil, spleen, and thymus).No unexpected staining was seen in the tissues examined.

Example 14 Cytokine Release, Complement Activation, and Tolerability

Cytokine Release in Human Whole Blood Treated with ICOS.33 IgG1f S267E

This study was designed to assess cytokine responses in human peripheralblood cells after treatment with ICOS.33 IgG1f S267E on fresh wholeblood samples.

Fresh normal sodium-heparinized whole blood (100 μL) was added to96-well round bottom plates. 100 μL of ICOS.33 IgG1f S267E or ICOS.33diluted in AIM V serum-free medium, isotype control anti-KLH-hIgG1-2F5mAb, or TGN (5.11A1) anti-CD28 mAb were added to the wells to obtain afinal antibody concentration of 10 μg/mL per well and a final volume of200 μL per well. SEB (100 μL) diluted in AIM V medium was added to thewells for a final concentration of 100 ng/mL SEB to obtain a finalvolume of 200 μL per well. CD3-CD28 (100 μL) diluted in AIM V medium wasadded to the wells for a final concentration of 1 μg/mL CD3-CD28 and afinal volume of 200 μL per well. LPS (100 μL) diluted in AIM V mediumwas added to the wells for a final concentration of 10 μg/mL LPS and afinal volume of 200 μL per well. Plates were incubated in an incubatorat 5% to 7% CO₂ atmosphere for 20 hours at 37° C. Plasma cell culturesupernatants from each well were harvested after 20 hours and stored at−20° C. Samples were shipped to BMS Lawrenceville, N.J. (LVL) in adry-ice container for assay performance.

To assess for cytokine secretion, 12 μL of premixed standards, controls,and samples were transferred to the assay plates. Magnetic beads (6 μL)were added to each 384-well plate, then sealed and incubated for twohours at room temperature on a plate shaker. After two hours ofincubation, the magnetic beads were washed twice, and 6 μL of detectionantibodies were added into each well. Plates were sealed again andincubated at room temperature on a plate shaker.Streptavidin-phycoerythrin (6 μL) was added to each well containing thedetection antibodies, then incubated for 30 minutes at room temperature,and washed twice using a plate washer. Sheath fluid (80 μL) was added toeach well, and beads were re-suspended for five minutes on a plateshaker. Plate samples were read by using the Bioplex 3D instrument arraysystem. Raw data were measured as mean fluorescent intensity (MFI).Concentration (pg/mL) was calculated by Xponent software.

A panel of 75 cytokines was assessed in blood from eight human normaldonors for cytokine release mediated by ICOS.33 IgG1f S267E. Addition ofICOS.33 IgG1f S267E to donor whole blood did not mediate cytokinesecretion in comparison to the isotype control. These data showed thatICOS.33 IgG1f S267E treatment does not lead to cytokine release syndrome(CRS) in whole blood.

Intermittent-Dose Intravenous Toxicity Study in Monkeys

This study was conducted to determine the potential toxicity and thebiological activity of ICOS.33 IgG1f S267E when given intravenously tomonkeys either once weekly or once every three weeks for a one-monthperiod to evaluate the reversibility of any observed changes, todetermine systemic exposures to ICOS.33 IgG1f S267E, to assess immuneresponses, and to provide data to support the use of ICOS.33 IgG1f S267Ein humans. ICOS.33 IgG1f S267E was administered intravenously as a slowbolus injection at doses of 0 (vehicle, once weekly on Days 1, 8, 15,22, and 29), 1.5 mg/kg (once every 3 weeks on Days 1 and 22), 15 mg/kg(once weekly), or 75 mg/kg (once weekly) to groups of five femalemonkeys and five male monkeys. All doses were administered at 2 mL/kg ina vehicle/carrier consisting of 20 mM histidine, 260 mM sucrose, 50 μMdiethylene triamine pentaacetic acid and 0.05% (w/v) polysorbate 80 (pH6.0). As potential pharmacodynamics measures at least in part, allmonkeys were immunized with keyhole limpet hemocyanin (KLH, immunogen tostimulate primary response), viral vectors Adenovirus-5 (Ad5)-Gag andAd5-Nef (immunogen to stimulate antigen-specific CD8 T cell response),and tetanus toxoid (immunogen to stimulate secondary response) on Day 1.For example, immunizing with tetanus toxoid allows expansion of thenumber of T cells specific to tetanus toxoid, and allows PK/PDevaluation of an antigen-specific population.

Criteria for evaluation included survival, toxicokinetics, clinicalobservations (including feeding behavior), body weights, physical(including respiratory, cardiovascular, and neurologic) andophthalmologic examinations, clinical pathology evaluations,immunogenicity assessment (of anti-ICOS.33 IgG1f S267E antibody; ADA),immunotoxicological and pharmacological assessments (including receptoroccupancy and receptor expression on CD4 helper T cells,T-cell-dependent antibody response (TDAR) to KLH or tetanus toxoid,peripheral blood lymphocyte phenotyping, T-cell activation,antigen-specific T-cell phenotyping, and ex vivo recall response to KLH,Gag, or Nef peptides), organ weights, and gross and microscopicpathology analyses. Scheduled necropsies were conducted after 1 month(three/group/sex) and following an 8-week recovery period(two/group/sex).

After repeated dosing, mean ICOS.33 IgG1f S267E systemic exposures(AUC[0-T]) increased approximately dose proportionally from 15 mg/kg to75 mg/kg (once weekly) with no substantial sex differences observed atall doses. After repeated dosing at 1.5 mg/kg (once every three weeks),mean ICOS.33 IgG1f S267E systemic exposures (AUC[0-504h]) were lower(0.4×) than those following dosing on Day 1, whereas AUC(0-168h) valuesafter repeated dosing at 15 mg/kg and 75 mg/kg (QW) were slightly higher(2.1-fold to 2.6-fold) than those following dosing on Day 1 suggestingaccumulation.

Treatment-emergent ADA responses were detected in 8 and 2 of 10monkeys/group at 1.5 mg/kg (once every three weeks) and 15 mg/kg (onceweekly), respectively, on or after Day 8. During the recovery phase,ADAs were only detected in monkeys at 1.5 mg/kg. After repeated dosing,serum ICOS.33 IgG1f S267E concentrations in monkeys with ADAs weregenerally immeasurable (i.e., <lower limit of quantification; LLOQ) orlower than those in monkeys with no ADAs at 1.5 mg/kg and 15 mg/kg, andthe presence of ADAs contributed to lower mean AUC value at 1.5 mg/kg.

The toxicokinetic summary for ICOS.33 IgG1f S267E is presented in Table28.

TABLE 28 Toxicokinetic Summary - Mean Sex-Combined Values ICOS.33 IgG1fS267E 1.5 mg/kg 15 mg/kg 75 mg/kg Parameter Period (Q3W) (QW) (QW) CmaxDay 1   42.6   377 2,010 (μg/mL) Day 22   39.2/47.4^(a) 680/733^(a)3,790 AUC(0-168 h) Day 1 3,520 34,200 176,000 (μg · h/mL) Day 222,860^(b)/4,610^(a) 71,800/84,600^(a) 452,000 AUC(0-504 h) Day 16,240^(c) NA NA (μg · h/mL) Day 22 2,510^(d)/NA^(a) NA NA ^(a)Valueswere calculated with the inclusion/exclusion of the data from animalswith detectable treatment-emergent ADAs on or/and after Day 8 (168 hoursfollowing the first dose). ^(b)Mean systemic exposure value was averagedfrom individual AUC(0-72 h) and AUC(0-168 h) values. ^(c)Mean systemicexposure value was averaged from individual AUC(0-168 h), AUC(0-336 h),and AUC(0-504 h) values. ^(d)Mean systemic exposure value was averagedfrom individual AUC(0-72 h), AUC(0-168 h), AUC(0-336 h), and AUC(0-504h) values. NA = Not applicable

ICOS.33 IgG1f S267E was well tolerated at all doses with no ICOS.33IgG1f S267E-related clinical observations or effects on body weight,physical (including respiratory, cardiovascular, and neurologic) andophthalmologic evaluations, hematology, coagulation, serum chemistry,urinalysis, organ weights, and gross or microscopic pathology. Inaddition, there were no ICOS.33 IgG1f S267E-related effects on TDAR totetanus toxoid, absolute numbers of cytotoxic T cells, B cells, and NKcells, T cell subtypes (including naive CD4 T cells, effector memory CD4T cells, CD25+ activated CD4 T cells, HLA-DR+ activated CD4 T cells,naive CD8 T cells, effector memory CD8 T cells, CD25+ activated CD8 Tcells, and HLA-DR+ activated CD8 T cells), CD8+ T cell proliferation,and ex vivo recall responses at any dose tested.

Evidence of ICOS.33 IgG1f S267E-mediated effects was noted at all doses.ICOS receptor expression on CD4 helper T cells was close to 0% at fourhours post dose on Day 1 at all doses, which suggested down regulationand/or internalization of the ICOS receptor, and generally stayed lowthrough the dosing and recovery period at ≥15 mg/kg. Low ICOS receptorexpression precluded meaningful assessment of ICOS receptor occupancy.At 1.5 mg/kg administered once every three weeks, ICOS receptorexpression on CD4 helper T cells began to recover after Day 8, increasedto 41% prior to dosing on Day 22, decreased to 4% following dosing onDay 22, and increased to 42% on Day 29. A full recovery of receptorexpression was observed by Day 43 (91%). Receptor occupancy generallycorrelated with receptor expression (e.g., 71% and 85% RO on Days 22[prior to dosing] and 29). In general, ICOS receptor expression levelswere inversely correlated with serum ICOS.33 IgG1f S267E concentrations.This was consistent with the conclusion that the ICOS.33 IgG1f S267Eantibody has caused loss of the receptor.

There was dose-independent suppression of keyhole limpet hemocyanin(KLH)-specific IgM (up to 52% on Day 8) and IgG responses (up to 78% onDay 29) relative to vehicle control. Suppression of T-cell-dependentantibody response to KLH by ICOS.33 IgG1f S267E may represent analternative mode of action, and has been observed in a previous study incynomolgus monkeys. Although not bound by any mechanism, suppression ofTDAR by an agonist of the ICOS co-stimulatory pathway may relate toimpaired agonism of T helper cells as a result of early and sustaineddownregulation of ICOS expression.

Other ICOS.33 IgG1f S267E-related effects at all or some of the doselevels during dosing and/or recovery period included decreases in meanabsolute numbers of total T cells and CD4 helper T cells, percent CD4 Tregulatory cells, percent central memory CD4+ T cells, percent centralmemory CD8+ T cells, percent Ki67+ CD4+ T cells, and percent Gag+ andNef+ CD8 T cells.

In conclusion, ICOS.33 IgG1f S267E was clinically tolerated by monkeysfor one month at intravenous doses≤75 mg/kg administered once weekly.ICOS.33 IgG1f S267E-related effects were noted at all doses, asdemonstrated by ICOS receptor expression and receptor occupancy changes,suppression of T-cell-dependent antibody response to KLH, decreasedlevels of certain T cell subsets, decreased CD4− T cell activation, anddecreased percentages of antigen specific CD8 T cells. Many of thesechanges were still apparent by the end of the recovery period at ≥15mg/kg QW consistent with continued ICOS.33 IgG1f S267E exposurethroughout the recovery period and the subsequent sustaineddownregulation of ICOS receptor expression at these doses. The lowerdose of 1.5 mg/kg administered once every three weeks resulted in lowerserum ICOS.33 IgG1f S267E concentrations after the first dose andallowed receptor recovery on the cell surface before the second dose.There were no adverse ICOS.33 IgG1f S267E-related findings. Thus, theno-observed-adverse-effect level (NOAEL) was considered to be 75 mg/kg(mean AUC[0-168h] of 452,000 μh/mL). In addition, for potentialdetermination of the maximum recommended human starting dose, 75 mg/kgwas also considered the highest non-severely toxic dose (HNSTD).

Single-Dose Intravenous Pharmacokinetics and Receptor Occupancy Study inMonkeys

The pharmacokinetics of ICOS.33 IgG1f S267E was evaluated in proteinnaive monkeys. All monkeys were immunized intramuscularly with 2.5 mg ofkeyhole limpet hemocyanin (KLH). Following the immunization, monkeyswere intravenously administered ICOS.33 IgG1f S267E in 20 mM histidine(pH 6.0), 250 mM sucrose buffer, 50 μM pentetic acid (DPTA) and 0.05%polysorbate 80 at doses of 0, 1 mg/kg, or 10 mg/kg (N=2/sex for vehicleand 1 mg/kg and 10 mg/kg groups) via femoral vein. Serial blood samples(about 0.5 mL) were collected at pre-dose and 6, 24, 72, 168, 240, 336,408, 504, 672, 840, and 1008 hours post dose. Blood samples were allowedto coagulate and then centrifuged at 4° C. (1500-2000×g) to obtainserum. Serum samples were stored at −20° C. and delivered for analysison dry ice. Samples not analyzed on the day of receipt were storedfrozen in a freezer set to maintain a temperature of ≤70° C. untilanalyzed.

Cynomolgus monkey serum samples were analyzed using a qualified Gyros®immunoassay for the detection of ICOS.33 IgG1f S267E. Biotinylated humanICOS mG1 (Lot No 22Oct2015-Biotin) was used as a capture molecule forICOS.33 IgG1f S267E. Samples, standards, and QCs were brought up to afinal matrix concentration of 10% cynomolgus serum and loaded intoGyrolab. Wash 2 V2 Wizard method with Gyrolab Bioaffy 200 CD was used.After final wash steps the captured ICOS.33 IgG1f S267E was detectedusing an Alexa 647 labeled mouse anti-Hu IgG Fc-specific monoclonalantibody, clone 10C7 (Lot No 15C3483473-10C7A) as the detectionmolecule. The concentration of ICOS.33 IgG1f S267E in cynomolgus serumsamples was calculated from fluorescence intensity as measured byGyrolab using a 4-parameter logistic (4-PL) calibration curve generatedfrom ICOS.33 IgG1f S267E calibrators.

The range of the ICOS.33 IgG1f S267E calibration curve was from 3 ng/mLto 30,000 ng/mL in cynomolgus monkey serum. The upper and lower limitsof quantification were 30,000 ng/mL and 3 ng/mL, respectively (i.e.,ULOQ 30000 ng/mL, LLOQ 3 ng/mL). Quality control samples were preparedat 20 ng/mL, 200 ng/mL, 2,000 ng/mL, and 20,000 ng/mL in cynomolgusmonkey serum and analyzed on each CD to ensure acceptable assayperformance. Calibrators, QCs, and samples were diluted 10-fold in PTB.Assay performance was within the acceptable range: % CV of the standardswas below 25%, and QC recovery was within ±30% of the nominal values.

Monkey serum samples were analyzed by ABO/BAS, Lawrenceville, N.J.,using a qualified electrochemiluminescence immunoassay on the Meso ScaleDiscovery (MSD) platform for the presence of anti-ICOS.33 IgG1f S267EADA. ICOS.33 IgG1f S267E mouse anti-idiotypic antibody cell supernatantwas used to prepare positive control (PC). Biotinylated ICOS.33 IgG1fS267E was used as a capture molecule and ICOS.33 IgG1f S267E labeledwith Sulfo Tag was used as a detection reagent. The biotinylated ICOS.33IgG1f S267E and Sulfo Tag-labeled ICOS.33 IgG1f S267E were diluted inPTB and combined to generate a master mix with final concentration ofbiotinylated ICOS.33 IgG1f S267E of 1,000 ng/mL and 1,000 ng/mL of SulfoTag-labeled ICOS.33 IgG1f S267E. Samples were diluted at 10% minimumrequired dilution (MRD) in the master mix and incubated at 22° C. for 2hours. The master mix was then transferred into a streptavidin-coatedMSD plate at 50 μL/well. After another hour of incubation at 22° C., theplate was washed and was added with the MSD read buffer. The plate wasthen read immediately on the MSD Sector Imager 6000. The presence ofdetectable anti-ICOS.33 IgG1f S267E antibodies in monkey serum sampleswas determined using the ratio of sample signal to negative samplesignal.

Monkey serum samples were analyzed by BAR, Lawrenceville, N.J.Cynomolgus monkey serum samples were analyzed for “total” ICOS.33 IgG1fS267E using direct trypsin digestion reversed phased liquidchromatography tandem mass spectrometry (LC/MS/MS). Monkey serum sampleswere also analyzed for deamidated and unmodified ICOS.33 IgG1f S267E atposition N329 using immunoaffinty enrichment target capture LC/MS/MS.Standard curves defining the range of the assay were prepared incommercially-obtained cyno serum and analyzed with the study samples asa complete analytical set. Concentrations for “total” ICOS.33 IgG1fS267E were reported in g/ml via Excel spreadsheet for toxicokinetic andpharmacokinetic interpretation.

PK parameter values were calculated using noncompartmental analysismethod (Phoenix WinNonlin 6.4, Certara, Princeton, N.J.). Exposurevalues below the lower limit of quantification (LLOQ: <10 ng/mL (0.07nM) for ICOS.33 IgG1f S267E) were not used in the analysis. The areaunder the curve from time 0 to the last sampling time (AUC(0-T)) werecalculated using a combination of linear and log trapezoidal summations.

The PK parameters of ICOS.33 IgG1f S267E following a single intravenousdose of 1 mg/kg and 10 mg/kg to cynomolgus monkeys are summarized inTable 29. After intravenous administration, the plasma concentrations ofICOS.33 IgG1f S267E exhibited a bi-exponential decline. Acceleratedclearance was observed in three out of four monkeys in 1 mg/kg groupafter Day 7. As a result, only the concentration time data up to Day 14were used for all animals in the 1 mg/kg dose group for analysis, andAUC (0-14d) was reported to eliminate influence of ADAs. Immunogenicitytesting of the plasma samples suggested that five out of eight monkeysenrolled in the study developed ADAs, and that the monkeys with higherADA levels showed faster clearance at the 1 mg/kg dose. AUC (0-42d) wasreported for the 10 mg/kg group. ICOS.33 IgG1f S267E exhibited close todose-proportional increase in Cmax and AUC(0-T) and AUC(0-INF). With thedose increment at the ratio of 1:10, the Cmax in male and female monkeysincreased at the ratio of 1:8 and 1:8, respectively; and the AUC(0-T)increased at the ratio 1:16 and 1:11, respectively, and the AUC(0-INF)increased at the ratio 1:11 and 1:11, respectively.

The concentrations of intact ICOS.33 IgG1f S267E, and the deamidatedproduct after a 10 mg/kg intravenous dose were quantified using LCMS/MS.The concentrations of the deamidated product ranged between 0.5% to 8%of total ICOS.33 IgG1f S267E at all measured time points. The AUC(0-42d) for the deamidated product was 2.9% of exposure of total ICOS.33IgG1f S267E.

TABLE 29 Pharmacokinetic Summary ICOS.33 IgG1f S267E 1 mg/kg^(a,c) 10mg/kg^(b,c) Parameter M F Mean M F Mean Cmax (μM)  0.168 ± 0.006 0.161 ±0.006 0.165 ± 0.006  1.4 ± 0.019   1.3 ± 0.046 1.38 ± 0.02  Thalf (day)14 ± 3  11 ± 0.7  13 ± 2.7  14 ± 5.2   14 ± 2.3 14 ± 2.7 AUC(0-T) 1.28 ±0.2 1.5 ± 0.7 1.2 ± 0.1  21 ± 0.5 16.9 ± 0.5 19 ± 0.5 (μM · day)AUC(0-INF)   2.3 ± 0.5^(d)    2 ± 0.09^(d) 2.17 ± 0.2^(d ) 25.9 ± 2.5 20.4 ± 2.3 23 ± 3.8 (μM · day) ^(a)AUC(0-T) truncated at 14 days in 1mg/kg dose group ^(b)AUC(0-42 d) reported for animals in 10 mg/kg dosegroup ^(c)Number of monkeys = 2/sex ^(d)>20% of the AUC is extrapolated

Although increased C1q binding was observed in vitro, the absence ofovert clinical signs in the single-dose study in monkeys, and absence ofhemodynamic effects in a cardiovascular instrumented monkey model showedlow risk for complement activation. ICOS.33 IgG1f S267E was welltolerated when given intravenously as a single dose at 1 mg/kg or 10mg/kg to cynomolgus monkeys with a dose proportional increase inexposure. No adverse clinical pathology findings were observed.

Example 15 Anti-ICOS Antibody Binding Competition

Epitope binning experiments were conducted to determine which anti-ICOSantibodies compete with which others for binding to huICOS. Epitopebinning is a process that uses a competitive immunoassay to testantibodies in a pairwise combinatorial manner, and antibodies thatcompete for the same binding region, that is, the same or a closelyrelated epitope of an antigen, are grouped together into bins. Pairwisecompetition between anti-huICOS antibodies was determined as follows. Areference antibody (i.e., ICOS.33, 20H4, 27B9, 23B6, 12D10, 23A10, 15B7,12F3, 13B4, 17H9, 26E11, 23H5, 6D1, 12A9, 5C4, 10B10, 17C4, 1D7, 21E1,9F11, 15H11, 25B10, 8A10, 4D11, 6D5, 7C6, 26E9, 3E8, 16H4, 25E4, or2644) was bound to the surface of a sensor chip, a test antibody waspre-incubated with a huICOS polypeptide construct in a mixture, and thepre-incubated mixture was flowed over the sensor chip to determine thedegree to which the test antibody interferes with binding of the huICOSpolypeptide construct to the reference antibody on the chip surface.Competition experiments were performed using a BIACORE® Surface PlasmonResonance (SPR) instrument. Specifically, a reference anti-huICOSantibody was immobilized onto Sensor Chip CM5 chip (Series S, GEHealthcare CAT #BR-1005-30) surfaces, flowcell2, flowcell3 & flowcell4(5000 resonance units, RUs), and flowcell1 was used as a negativecontrol. A test antibody (i.e., ICOS.33, 20H4, 27B9, 23B6, 12D10, 23A10,15B7, 12F3, 13B4, 17H9, 26E11, 23H5, 6D1, 12A9, 5C4, 10B10, 17C4, 1D7,21E1, 9F11, 15H11, 25B10, 8A10, 4D11, 6D5, 7C6, 26E9, 3E8, 16H4, 25E4,or 2644) was diluted to 120 μg/mL (2×) at starting concentration. Aseries of dilutions of the test antibody was made by diluting 1:3concentration of antibody with buffer for seven different concentrationsand a control sample (with 0 μg/ml) to obtain a titration curve. Eachantibody concentration series was divided in half. In the first half ofthe concentration series, 40 nM (2λ) human ICOS antigen (e.g. huICOS/Fc)was added to make the final concentration series (60 μg/ml-0.0 μg/ml)and 20 nM of final antigen concentration in each well. In the secondhalf of the concentration series, in place of antigen, buffer was addedto have the antibody diluted to the same concentration, and this halfwas treated as the blank. Complexes of the test anti-ICOS antibodies andhuICOS/Fc were incubated for two hours. 40 μL complexes were injected onthe reference antibody-coated surface at a 30 μL/min. A BIACORE® T200SPR instrument was used and the running buffer in HBE-EP, GE HealthcareCAT #BR-1001-88, filtered, degassed, 0.01 M HEPES, pH 7.4, 0.15 NaCl, 3mM EDTA, 0.005% Surfactant P20. The surface was regenerated with 25 mMNaOH (order code: BR-1003-58, GE Healthcare) at 100 μL/min for fiveseconds. The data were analyzed using Microsoft Excel where theconcentration of test antibodies was plotted against the correspondingresponse unit to obtain titration curves.

The binding competition experiments determined that antibodies ICOS.33,20H4, 27B9, 23B6, 12D10, 23A10, 15B7, 12F3, 13B4, 17H9, 26E11, 23H5,6D1, 12A9, 5C4, 10B10, 17C4, 1D7, 21E1, 9F11, 15H11, 25B10, 8A10, 4D11,6D5, 7C6 and 26E9 cross-compete with each other, and block ligand(B7-H2; ICOS-L) binding to huICOS. Antibodies 3E8, 16H4 and 25E4cross-compete with each other but do not block ligand binding to huICOS.In contrast, while antibody 2644 was found to cross-compete withantibody 3E8, it was also able to block ligand binding to ICOS.

Example 16 Anti-ICOS Antibody Epitope Mapping

Anti-ICOS Antibody Epitope Mapping by Yeast Display

The epitopes for anti-huICOS antibodies 3E8 and ICOS.4 were determinedby displaying randomly mutagenized variants of the extracellular domainof human ICOS (residues 21-134 of NP_036224.1, provided as SEQ ID NO:173) by yeast cells (Saccharomyces cerevisiae), and sorting the yeastcells based on their binding or not binding to particular antibodies.Selected yeast cells were amplified and subjected to additional roundsof selection based on their ability to bind to anti-ICOS antibodiestested. See, e.g., Chao et al. (2004) J. Mol. Biol. 342:539. Sequencesfor huICOS variants were determined for the resulting yeast and analyzedfor the effects of each residue on antibody binding. The binding epitopefor the antibodies of the present invention was determined as the lociwithin the huICOS sequence where single amino acid mutations disruptbinding to the anti-huICOS antibodies of the present invention.

Briefly, error-prone PCR was used to clone human ICOS-encoding DNA(encoding residues 21-134 of SEQ ID NO: 1) into constructs allowingexpression of the huICOS variants as the amino-terminal portions offusion proteins further comprising a c-myc tag sequence and yeast cellwall protein Aga1p. Such constructs, when expressed in yeast(Saccharomyces cerevisiae), display the variant huICOS polypeptides onthe surface of yeast cells, anchored to the cell surface by the Aga1ppolypeptide. The c-myc tag was used as a positive control to sort yeastcells displaying huICOS fusion proteins. These yeast cells were thenfurther sorted for those that expressed properly folded huICOS-fusionproteins (as determined by binding of a control mouse anti-huICOSantibody detected by an allophycocyanin (APC)-labeled goat anti-mouseIgG secondary), but did not bind to the antibodies of the presentinvention (as determined by detection with a phycoerythrin (PE) labeledgoat anti-human IgG as a secondary). These selected yeast cells werepooled, amplified, and used in a subsequent round of selection. ThehuICOS sequence was determined for constructs from yeast remaining afterselection.

Yeast populations binding to ICOS.4 and 3E8 show distinct mutationpatterns, indicating different epitopes were recognized by these twoantibodies. Analogous experiments were performed with antibody 9D5,which blocks ICOS-ligand binding to ICOS and which competes with ICOS.4.For the 9D5 experiments, a molecular model of the three dimensionalstructure of ICOS based on the crystal structure of the CTLA-4/B7-2complex (e.g. Stamper et al. (2001) Nature 410:608) was used todistinguish which amino acid residues are buried and which aresurface-exposed to determine which of the selected mutations were mostlikely antibody-specific contact residues (i.e., epitope residues) asopposed to mere structurally disruptive mutations. The yeast displayinferred epitopes for ICOS.4, 3E8 and 9D5 are provided in Table 30.Epitopes in Table 30 are presented as a list of residues in huICOS ofSEQ ID NO: 1, which includes the 20 amino acid signal sequence.Accordingly, residue numbers for mature huICOS (i.e., ICOS proteinwithout the signal sequence) would be the residues indicated in Table 30reduced by 20 (e.g., V48 with the signal sequences or V28 without thesignal sequence).

TABLE 30 Anti-ICOS mAb Epitopes Clone ICOS Residues (SEQ ID NO: 1)ICOS.4 V48, Q50, G70, S71, G72, F114, D115, P116, P117, P118, L123 3E8D64, K78, S79, L80, K81, F82, S85 9D5 P45, I47, P117, P118, K120

Analogous yeast display experiments were performed with ICOS-L (B7-H2)in place of anti-ICOS mAbs to determine which residues on ICOS arecritical to the ICOS/ICOS-L interaction, i.e. the binding site forICOS-L on ICOS. The ICOS-L binding site was determined to reside atresidues Q50, K52, F114, P117, P118, and F119 of ICOS, as provided atSEQ ID NO: 1. Inspection of the epitopes for anti-ICOS mAbs in Table 30suggests that ICOS.4 and 9D5 should block ICOS-L binding, whereas 3E8may not, which is consistent with what was observed experimentally (asdiscussed in Example 15 above).

Anti-ICOS Antibody Epitope Mapping by HDX-MS

Deuterium exchange experiments with antibodies ICOS.4 and 9D5 confirmedthat the region from S112 and L123 is contacted when ICOS is bound toICOS-L, which suggested a functional epitope region of residues 112-123of ICOS (SEQ ID NO: 1), or SIFDPPPFKVTL (SEQ ID NO: 203). This regionoverlaps with the C-terminal portion of the epitope determined by yeastdisplay, and represents the largest cluster of residues along theprimary sequence.

The epitopes for anti-huICOS antibodies ICOS.4 and 9D5 were determinedby hydrogen/deuterium exchange mass spectrometry (HDX-MS) see, e.g.,Epitope Mapping Protocols in Methods in Molecular Biology, Vol. 66, G.E. Morris, Ed. (1996) as described herein. ICOS-Fc was mixed with mAbsat 1:1 ratio and HDX-MS was run for one minute, 10 minutes, 4 hours induplicate.

Results show that ICOS.4 and 9D5 bind to the same discontinuous epitope,which is shown below (epitope is underlined) and in FIG. 1.

(SEQ ID NO: 1)MKSGLWYFFLFCLRIKVLTGEINGSANYEMFIFHNGGVQILCKYPDIVQQFKMQLLKGGQ 60ILCDLTKTKGSGNTVSIKSLKFCHSQLSNNSVSFFLYNLDHSHANYYFCNL SIFDPPPFK 120 VTLTGGYLHIYESQLCCQLKFWLPIGCAAFVVVCILGCILICWLIKKKYSSSVHDPNGEY 180MFMRAVNTAKKSRLTDVTL 199

Example 17 Expression of ICOS on Peripheral Blood and Tumor-InfiltratingLymphocytes from Lung, Kidney, and Colon Cancer Patients

Understanding ICOS expression on tumor-infiltrating lymphocytes (TIL) indifferent tumor types and patient populations helped identify therelevant disease indication and patient population for effective ICOS.33IgG1f S267E therapy, especially in combination with anti-PD-1 agentssuch as nivolumab. The frequency and magnitude of ICOS and PD-1expression on peripheral blood cells and TIL (CD8+ and CD4+ T cells)were profiled in non-small cell lung, renal cell, and colorectalcarcinoma (CRC) specimens.

Fresh tumor tissues and matching peripheral blood samples were obtainedfrom patients with lung cancer, kidney cancer, or CRC (ConversantBio, MTGroup, Benaroya) and shipped overnight at 4° C. in hypothermosol FRS(Biolife Solutions) and ACD Solution A (BD Biosciences), respectively.All samples were processed and stained within 24 hours of surgery. Tumortissues were weighed and dissociated using the Miltenyi dissociation kit(Miltenyi, Catalog 130-095-929), whereas peripheral blood cells wereisolated after lysis of red blood cells (RBC) in RBC Lysis Buffer(BioLegend, Catalog 420301). Cell suspensions (from tumor tissues orperipheral blood) were washed two times in HBSS (no Ca, no Mg), stainedwith NIR Viability Dye (Molecular Probes by Life Technologies, CatalogL34976), blocked with human AB serum in Dulbecco's phosphate-bufferedsaline (dPBS), and added to wells containing cocktails of antibodies(Table 31) for incubation on ice in the dark for 45 minutes. The cellswere then washed twice with dPBS/BSA/Na azide, fixed, and permeabilizedusing the FOXP3 buffer kit (BioLegend, Catalog 421403). Fluorescenceminus one (FMO) controls were prepared for all antibodies and used todetermine positive cell populations. Samples were acquired on theFortessa flow cytometer (BD Biosciences) and data were analyzed usingFlowJo Software (TreeStar).

As shown in Table 31, a panel was devised to examine expression ofmultiple markers, and ICOS expression on CD8+ and CD4+ T cells wasanalyzed.

TABLE 31 Antibodies Used For Immunofluorescence Staining For T CellSubsets Marker Clone Fluorophore Vendor Catalog CD3 SK7 BUV 395 BDBiosciences 564001 CD4 OKT4 BV 785 BioLegend 317442 FOXP3 206D AF647BioLegend 320114 CD25 4E3 PE-e610 eBioscience 61-0257-42 CD152 BN13 BV421 BD Biosciences 562743 CD45 HI30 AF700 BD Biosciences 560566Viability — Near IR ThermoFisher L10119 Scientific 2B4 C1.7 AF488BioLegend 329506 CD8a SK1 BV605 BD Biosciences 564116 ICOS C398.4A BV510BioLegend 313525 CD56 NCAM16.2 BV650 BioLegend 318343 PD-1 EH12.1 PEBioLegend 560795

For Treg, Teff, B cell, and NK cell staining, fresh tumors from head andneck, lung, CRC, and endometrial cancers were placed in a 6-well platerested on ice, immersed in 1-2 mL of dissociation media. The tumors werecut into small pieces, and the tumor solution was placed into the Douncehomogenizer for dissociation. Tumor solutions were filtered through a 70μm filter with additional dissociation media and centrifuged. Resultingcells were re-suspended in staining buffer. Fresh omentum metastatictumor tissue sample was dissociated using the Miltenyi dissociation kit(Miltenyi, Catalog 130-095-929). Frozen tumor samples were thawed andDNAase added dropwise (2 mL DNAase solution). Thaw medium (8 mL warmedin 37° C. bath) was added to the tumor and DNAase solution, and filteredthrough a 70 μm filter. Cells were centrifuged and re-suspended instaining buffer.

ICOS expression on TIL was assessed by FACS analysis. Tumor derived cellsuspensions were blocked with staining buffer containing the Near-IRDead Cell stain. Surface cell population markers were stained withantibodies (as shown in Table 32) to determine positive cell populationsfollowed by intracellular staining of FOXP3 after fixation andpermeabilization. Flow cytometric data was collected using a FortessaX-20 flow cytometer. After gating on FSC-SSC-Live/Dead markersparameters to exclude debris and dead cells, the frequency of ICOS+cells were determined for CD4+ Teff, Treg, CD8+ T cell, B cell, and NKcell subsets. Cd4+ Flow cytometric analysis was performed with FlowJoanalysis software.

TABLE 32 Antibodies Used For Immunofluorescence Staining of B Cells, NKCells, and T Cell Subsets Conjugate Target Company Catalog Clone AlexaCD8 BioLegend 301028 RPA-T8 Fluor ® 700 BUV395 CD8 BD Biosciences 563795RPA-T8 BUV737 CD14 BD Biosciences 564444 M5E2 BUV805 CD4 BD Biosciences564910 SK3 BV421 ICOS BioLegend 313524 C398.4A BV510 CD45 BioLegend304036 HI30 BV510 CD45RA BioLegend 304142 HI100 BV605 CD11c BioLegend301636 3.9 BV650 CD15 BioLegend 323034 W6D3 BV650 CD45 BD Biosciences563717 HI30 BV711 PD1 BD Biosciences 564017 EH12.1 BV786 CD3 BDBiosciences 563800 SK7 PE/Cy5 CD19 BioLegend 302210 HIB19 PE/Cy7 FOXP3eBioscience 25-4777-42 236A/E7 PE-eFluor ® CD56 eBioscience 61-0567-42CMSSB 610 PerCP/Cy5.5 HLADR BD Biosciences 560652 G46-6

ICOS expression was evaluated using the anti-ICOS C398.4a clone in wholeblood samples from 16 healthy donors and 14 lung cancer, 22 RCC, and 14CRC patients. Compared to healthy donors, the frequencies of ICOS+ CD4+T cells obtained from cancer patients were higher (Table 33, P<0.001 forall cancer patient groups compared to healthy donors, Mann-Whitneytest). Frequencies of ICOS+ CD8+ T cells from RCC patients weresignificantly higher compared to healthy donors (Table 33, P<0.01,Mann-Whitney). In lung cancer and CRC patient blood samples, thepercentages of ICOS+ CD8+ T cells were also higher than in healthy donorsamples without reaching statistical significance (Table 33).

Because higher frequencies were observed than reported in literature andbecause the C398.4a clone positively stained more T cells than the othercommonly used clone ISA-3,6,7,8,9,10 the frequencies of cells thatexpress high levels of ICOS (ICOShi) were also analyzed. Consistent withthe literature, CD8+ T cells expressed minimal amounts of ICOShi,comparable to background (Table 33). In CD4+ T cells, however, thefrequencies of ICOShi cells ranged on average from 3.0% in healthydonors to 4.9% in patients with RCC (Table 33, RCC vs. healthy: P<0.05,Mann-Whitney).

Next, ICOS expression was evaluated in TIL of 11 lung cancer, 21 RCC,and 8 CRC patients. Frequencies of ICOS+ CD4+ and ICOS+ CD8+ TIL weresimilar across tumor types (Table 34). As in peripheral blood, highexpression of ICOS by CD4+ and CD8+ TIL T cells was measured. Onaverage, a greater percentage of CD4+ T cells expressed high levels ofICOS than CD8+ T cells (Table 34). Co-expression of ICOS and PD-1 in TILwas also measured. High levels of PD-1 (PD-1hi) were expressed by ICOShiCD4+ TIL with large interpatient variability (Table 34). Compared toICOShi CD4+ TIL, a higher proportion of ICOShi CD8+ T cells co-expressedhigh levels of PD-1 (Table 34).

TABLE 33 Mean Frequencies ± SD of ICOS+ and ICOShi CD4+ and CD8+ T Cellsin Peripheral Blood Samples From Healthy Donors and Patients with CancerHealthy NSCLC RCC CRC (N = 16) (N = 14) (N = 22) (N = 14) % ICOS+ CD4+ Tcells 21 ± 7  43 ± 15 39 ± 16 42 ± 19 % ICOS+ CD8+ T cells 14 ± 8  23 ±14 25 ± 12 23 ± 14 % ICOS^(hi) CD4+ T cells 3.0 ± 1.8 3.5 ± 1.8 4.9 ±2.9 3.7 ± 2.4 % ICOS^(hi) CD8+ T cells 0.9 ± 0.7 0.9 ± 0.8 1.3 ± 0.9 0.9± 0.7 Abbreviations: ICOShi: Cells expressing high levels of ICOS; N:Number of samples; SD: Standard deviation; NSCLC: Non-small cell lungcancer; RCC: Renal cell carcinoma; CRC; Colorectal carcinoma

TABLE 34 Mean Frequencies ± SD of ICOS+, ICOShi, and PD-1hi ICOShi CD4+and CD8+ T Cells in TIL From Patients with Cancer NSCLC RCC CRC (N = 11)(N = 21) (N = 8) % ICOS+ CD4+ T cells 59 ± 21 53 ± 19 63 ± 14 % ICOS+CD8+ T cells 35 ± 19 35 ± 20 27 ± 21 % ICOS^(hi) CD4+ T cells 28 ± 15 19± 20 29 ± 12 % ICOS^(hi) CD8+ T cells 8.3 ± 7.2 6.5 ± 8.5 4.8 ± 4.5 %PD-1^(hi) ICOS^(hi) CD4+ T cells 43 ± 18 48 ± 23 33 ± 17 % PD-1^(hi)ICOS^(hi) CD8+ T cells 63 ± 16 71 ± 29 62 ± 23 Abbreviations: SD:Standard deviation; ICOShi: Cells expressing high levels of ICOS; PD-1:Cells expressing high levels of PD-1; TIL: Tumor-infiltratinglymphocytes; NSCLC: Non-small cell lung cancer; RCC: Renal cellcarcinoma; CRC: Colorectal carcinoma; N: Number of samples

Human tumor samples from patients with two lung adenocarcinomas, oneendometrial adenocarcinoma, one omentum metastasis of serous papillarycarcinoma, one liver metastasis of colorectal adenocarcinoma, and onehead and neck squamous cell carcinoma were dissociated and stained forflow cytometric analysis of ICOS expression on various lymphocytepopulations. Of the five different lymphocyte populations depicted (CD4+Teff, Tregs, CD8+ T cells, B cells, NK cells), CD4+ Teff and Tregsexpressed the highest frequencies of ICOS. On cell populations thatexpressed ICOS (CD4 Teff, Tregs, CD8 T cells, and NK cells), Tregsexpressed more ICOS on a per cell basis compared to other cell types.

In summary, ICOS was expressed at higher levels on CD4+ T cells than inCD8+ T cells on peripheral blood and TIL. ICOS expression was variableacross patients and was similar for the three tumor types tested. Onaverage, 33% to 48% of ICOShi CD4+ TIL and 62% to 71% of ICOShi CD8+ TILco-expressed high levels of PD-1. In addition, Tregs expressed higherlevels of ICOS than CD4+ Teffs, CD8+ T cells, NK cells, and B cells inthe human tumor microenvironment.

Example 18 A Dose Escalation and Combination Cohort Study to Evaluatethe Safety and Tolerability, Pharmacokinetics, and Efficacy of ICOS.33IgG1f S267E Alone or in Combination with One or More Anti-PD-1 Antibody,One or More Anti-PD-L1 Antibody, and/or One or More Anti-CTLA-4 Antibodyin Patients with Advanced Solid Tumors

Phase ½, open-label, study of ICOS.33 IgG1f S267E administered as amonotherapy or in combination with an anti-PD-1 antibody, an anti-PD-L1antibody, and/or an anti-CTLA-4 antibody (for example nivolumab and/oripilimumab) is conducted in participants with advanced solid tumors. Thestudy includes the following parts:

1) dose-escalation monotherapy (Preliminary Safety Cohorts and Part A);

2) dose-escalation combination therapy with either nivolumab (Part B) oripilimumab (Part C); and

3) dose expansion phase with either nivolumab (Part D) or ipilimumab(Part E).

Objectives

The primary objective of this study is to characterize the safety andtolerability of ICOS.33 IgG1f S267E administered alone and incombination with nivolumab or ipilimumab in participants with advancedsolid tumors.

Secondary objectives include exploring the preliminary efficacy ofICOS.33 IgG1f S267E administered alone and in combination with eithernivolumab or ipilimumab in participants with advanced solid tumors;characterizing the PK of ICOS.33 IgG1f S267E when administered alone andin combination with nivolumab or ipilimumab in participants withadvanced solid tumors; characterizing the immunogenicity of ICOS.33IgG1f S267E when administered alone and in combination with nivolumab oripilimumab in participants with advanced solid tumors; and monitoringtarget engagement of ICOS.33 IgG1f S267E administered alone and incombination with either nivolumab or ipilimumab in participants withadvanced solid tumors.

In addition, exploratory objectives include examining the associationbetween anti-tumor activity and specific biomarker measures in the tumortissue and in peripheral blood prior to treatment and followingadministration of ICOS.33 IgG1f S267E alone and in combination witheither nivolumab or ipilimumab; characterizing the relationship(s)between ICOS.33 IgG1f S267E PK alone and in combination with nivolumabPK or ipilimumab PK, and safety, efficacy, and/or clinical biomarkers;assessing the overall survival rate (OSR) in participants treated withICOS.33 IgG1f S267E alone and in combination with either nivolumab oripilimumab; characterizing the PK and immunogenicity of nivolumab andipilimumab when administered in combination with ICOS.33 IgG1f S267E;characterizing the immunogenicity of nivolumab and ipilimumab whenadministered in combination with ICOS.33 IgG1f S267E; assessing thepotential effect of ICOS.33 IgG1f S267E on QT interval corrected (QTc);and exploring associations between select peripheral blood biomarkersand incidence of adverse events (AEs) and serious adverse events (SAEs).

Overall Design

A schematic for the study design is shown in FIG. 27.

Monotherapy consists of two different cohorts as follows:

-   -   Preliminary Safety Cohorts: ICOS.33 IgG1f S267E administered as        monotherapy at 2 mg and 8 mg once every four weeks for 24 weeks.    -   Part A: ICOS.33 IgG1f S267E administered at 25 mg, 80 mg, 200        mg, 400 mg, and 800 mg once every four weeks for 24 weeks.        Parts B and C consist of different combination cohorts        comprising:    -   B1: ICOS.33 IgG1f S267E administered once every 12        weeks+nivolumab 480 mg once every 4 weeks at a starting dose        level of ICOS.33 IgG1f S267E recommended by the Bayesian        Logistic Regression Model (BLRM)-Copula model and available        PK/PD data from Part A.    -   B2: ICOS.33 IgG1f S267E once every 4 weeks+nivolumab 480 mg once        every 4 weeks at a dose level of ICOS.33 IgG1f S267E recommended        by the Bayesian Logistic Regression Model (BLRM)-Copula model        (BLRM-RD) and available PK/PD data from Part A.    -   C1: ICOS.33 IgG1f S267E once every 12 weeks+ipilimumab 3 mg/kg        once every 4 weeks at a starting dose level of ICOS.33 IgG1f        S267E recommended by the Bayesian Logistic Regression Model        (BLRM)-Copula model and available PK/PD data from Part A.    -   C2: ICOS.33 IgG1f S267E once every 4 weeks+ipilimumab 3 mg/kg        once every 4 weeks at a dose level of ICOS.33 IgG1f S267E        recommended by the Bayesian Logistic Regression Model        (BLRM)-Copula model and available PK/PD data from Part A.    -   Parts B1 and C1 are enrolled concurrently. Parts B2 and C2 are        enrolled only if additional safety, PK, or PD data is required        to optimize dose and/or schedule selection.

The doses of ICOS.33 IgG1f S267E for Parts B and C (combination withnivolumab or ipilimumab) are determined using all available safety(clinical and laboratory), PK, and target engagement/pharmacodynamicbiomarker data, as well as modeling recommendation within Bayesianhierarchical modeling framework, i.e., the BLRM-Copula model, byincorporating single-agent toxicity profiles of both ICOS.33 IgG1f S267E(Preliminary Safety Cohorts and Part A) and nivolumab or ipilimumab andany available combination toxicity profiles from Parts B and C (forsubsequent doses of ICOS.33 IgG1f S267E in Parts B and C), PK/PDmodeling, and do not exceed the maximum administered dose (MAD) ofICOS.33 IgG1f S267E monotherapy in the Preliminary Safety Cohorts andPart A. A dose level of ICOS.33 IgG1f S267E recommended by theBLRM-Copula model, i.e., BLRM-RD, is defined as a generic concept suchthat a BLRM-RD for any cohort is always based on all available and mostupdated information.

At no point does the dose of ICOS.33 IgG1f S267E administered incombination with nivolumab or ipilimumab (Parts B and C) exceed the doseof ICOS.33 IgG1f S267E that is demonstrated to be safe in themonotherapy dose-escalation arm (Part A), nor at any point duringcombination therapy in Parts B and C does the ICOS.33 IgG1f S267E doseexceed the highest dose determined to be tolerated in the monotherapydose-escalation arm (Part A). In addition, the starting dose level ofICOS.33 IgG1f S267E used in combination with nivolumab or ipilimumab(Parts B and C) is one dose level lower than a monotherapy (Part A) dosethat has cleared the DLT period.

Parts B1 and C1 consist of a PK/pharmacodynamic sub-study aimed toexplore the kinetics of ICOS-receptor downregulation and re-expression(and/or change in selected target engagement/pharmacodynamic biomarkers)following administration of ICOS.33 IgG1f S267E in the presence ofmultiple doses of nivolumab once every 4 weeks (Part B1) or ipilimumabonce every 4 weeks (Part C1).

Different doses of ICOS.33 IgG1f S267E are administered in Parts B1 andC1:

-   -   Doses that induce or are predicted to induce different levels of        ICOS receptor downregulation, including at least one dose that        induces near-complete receptor downregulation (and/or change in        selected target engagement/pharmacodynamic biomarkers) for a        duration of at least 4 weeks. These dose levels allow        characterization of the ICOS receptor re-expression kinetics        after near-complete downregulation for a period of time equal        to, less than, and/or exceeding the dosing intervals used in        Part A. By understanding ICOS receptor kinetics, it may help        inform testing ICOS.33 IgG1f S267E dosing intervals in future        study(ies).    -   BLRM-RD: Dose levels are determined based on all available        safety (clinical and laboratory) and PK data, as well as changes        in peripheral target engagement markers (e.g., ICOS        downregulation on T cells and ICOS+B cells) from previous and        completed portions of current cohorts, and/or the        BLRM/BLRM-Copula model whenever applicable.

After 24 weeks of monotherapy treatment, or two years of combinationtherapy, the participant may be eligible for retreatment. For Part A,scans are collected centrally and may be reviewed by blinded independentcentral review (BICR) at a later date, or at any time during the study.For Parts B and C, scans are collected centrally to be reviewed in realtime by BICR.

Physical examinations, vital sign measurements, 12-leadelectrocardiogram (ECG), and clinical laboratory evaluations areperformed at selected times throughout the dosing interval.

Participants are closely monitored for AEs throughout the study. Bloodis collected at 30-, 60-, and 100-day follow-up visits after studytreatment administration for PK analysis.

Participants complete up to four phases of the study: screening,treatment, safety follow-up, and response/survival follow-up, asdescribed below. Total duration of participation in the study isapproximately 2 years.

Tetanus Vaccine

All patients in Parts A, B, and C receive an approved tetanus vaccine.Administration of a potent recall antigen such as tetanus toxoid primesthe immune system, induces an immune response, and promotes a moreimmunogenic state.

The ability of ICOS.33 IgG1f S267E to enhance a recall response will bedetermined by monitoring antibodies to tetanus and proliferative andcytokine responses by CD4+ T-cells after tetanus vaccination.Approximately 70% of the general population has protective antibodies totetanus. However, cellular immune responses are usually detectable inthe peripheral blood one month after tetanus vaccine. Tetanus has beenused as a reporter antigen in cancer patients receiving immunotherapywith vaccines and can be easily monitored. Consequently, tetanusvaccination may provide potent recall response with ICOS.33 IgG1f S267Ealone and in combination with nivolumab or ipilimumab.

Screening

The screening phase lasts for up to 28 days and take place prior to thefirst administration of study treatment. During the screening phase, theparticipant's initial eligibility is established, and written informedconsent is obtained. Tumor biopsies are collected for all participants,centrally evaluated for ICOS expression by immunohistochemistry, andresults are evaluated before administration of the first dose of studytreatment. Participants are enrolled using the Interactive ResponseTechnology (IRT).

Treatment Phase

The treatment phase in the Preliminary Safety Cohort and Part A consistsof up to six four-week treatment cycles (1 cycle=28 days). In thePreliminary Safety Cohort and Part A, each treatment cycle consists ofICOS.33 IgG1f S267E monotherapy for a total of 24 weeks.

Dose levels for Parts B and C are determined based on all availablesafety (clinical and laboratory) and PK data, as well as changes inperipheral target engagement markers (e.g., ICOS downregulation on Tcells and ICOS+B cells) from previous and completed portion of currentcohorts, and are guided by the BLRM/BLRM-Copula model wheneverapplicable.

In Parts B1 and C1, four week cycles are used, such that ICOS.33 IgG1fS267E+nivolumab or ipilimumab are administered starting on Cycle 1Day 1. Nivolumab and ipilimumab are administered on Day 1 of each cycle.ICOS.33 IgG1f S267E is administered once every 12 weeks, or on Day 1 ofevery third cycle (Cycle 1 Day1, Cycle 4, Day1, Cycle 7 Day1, etc.).Participants on Parts B1 and C1 continue treatment for up to a total of2 years.

The treatment phase in Parts B2 and C2 consists of ICOS.33 IgG1fS267E+nivolumab or ipilimumab administered on Day 1 of each cycle for upto a total of 2 years, and are only enrolled if additional safety, PK,or PD data is required to optimize dose and/or schedule selection.

Following each treatment cycle, the decision to treat a participant withadditional cycles of study treatment is based on tumor assessmentevaluations performed every 12 weeks (once every 12 weeks±1 week) andcompleted before the first dose in the next cycle. Tumor progression orresponse endpoints are assessed using Response Evaluation Criteria InSolid Tumors (RECIST) v1.1 or Prostate Cancer Working Group 3 (PCGW3)Guidelines, for prostate only (Scher et al., 2016. Trial Design andObjectives for Castration-Resistant Prostate Cancer: UpdatedRecommendations From the Prostate Cancer Clinical Trials Working Group3. Clin Oncol. 34(12):1402-1418).

Treatment beyond progression with additional cycles of study treatmentis allowed for up to a maximum of 24 weeks for Part A and two years forParts B, C, D, and E in select participants with initial RECIST v1.1 orPCGW3 (prostate only) defined PD after discussion and agreement betweenthe Principal Investigator and the BMS Medical Monitor/Study Directorthat the benefit/risk assessment favors continued administration of thestudy treatment (e.g., participants are continuing to experienceclinical benefit as assessed by the investigator, tolerating treatment,and meeting other specific criteria).

Participants with a response of unconfirmed progressive disease (PD),stable disease (SD), partial response (PR), or complete response (CR) atthe end of a given cycle continue to the next treatment cycle.Participants are generally allowed to continue study treatment until thefirst occurrence of 1) completion of the maximum number of cycles, 2)confirmed PD, 3) clinical deterioration suggesting that no furtherbenefit from treatment is likely, 4) intolerability to therapy, or 5) aparticipant meeting criteria for discontinuation of study treatment.Individual participants with confirmed CR are given the option todiscontinue study treatment on a case-by-case basis after specificconsultation and agreement between the investigator and BMS MedicalMonitor/Study Director in settings where benefit/risk justifydiscontinuation of study treatment.

Safety Follow-Up

Upon completion of 24 weeks of study treatment for Part A (or up to amaximum of 48 weeks if applicable) or two years for Parts B, C, D, and E(or up to a maximum of four years, if applicable), the decision is madeto discontinue the participant from study treatment (e.g., at end oftreatment [EOT]) and all participants enter the safety follow-up period.

For participants who complete all scheduled cycles of therapy, the EOTvisit is the same as the last scheduled and completed on-treatment visitand the start of the Week 1 safety follow-up visit. For participants whodo not complete all scheduled cycles of study treatment, the EOT visitis the most recent on-treatment visit (with all available safety andresponse data) and is considered the start of the safety follow-upvisit.

After the EOT visit, all participants are evaluated for any new AEs forat least 100 days after the last dose of study treatment. Follow-upvisits to monitor for AEs occur at Days 30, 60, and 100 after the lastdose or on the date of discontinuation (±7 days). All participants arerequired to complete the 3 clinical safety follow-up visits regardlessof whether or not they start new anti-cancer treatment, except thoseparticipants who withdraw consent for study participation.

Survival Follow-Up

After completion of the safety follow-up visits, all participantstreated with monotherapy and combination therapy enter the survivalfollow-up period. Participants are followed approximately every 3 months(12 weeks) until death, loss to follow-up, withdrawal of consent, orconclusion of the study, whichever comes first. The duration of thisphase is up to two years from the first dose of study treatment,although a longer follow-up period is considered in selected cases if anefficacy signal is apparent.

Response Follow-Up

After completion of the Safety Follow-up period, participants withongoing SD, PR, or CR at the EOT visit enter the Response Follow-upperiod. This period occurs simultaneously with the Survival Follow-upperiod for the mentioned participants. Participants continue to haveradiologic and clinical tumor assessments approximately every 3 months(12 weeks) until death, loss to follow-up, withdrawal of consent, orconclusion of the study, whichever comes first. Radiological tumorassessments for participants who have ongoing clinical benefit continuesto be collected after participants complete the survival phase of thestudy. Participants who have disease progression following initialcourse of study treatment are not evaluated for response beyond the EOTvisit and are allowed to receive other tumor-directed therapy asrequired. If the participant discontinues treatment for any reason otherthan PD, radiological follow-up continues until the participant receivesadditional treatment.

Treatment with Additional Cycles Beyond 24 Weeks

All participants are treated for 24 weeks of monotherapy or combinationtherapy unless criteria for study treatment discontinuation are metearlier. All participants completing treatment with ongoing diseasecontrol (CR, PR, or SD) or unconfirmed PD are eligible for an additional24 weeks of study treatment for Part A or for a total of two years forcombination therapy on a case-by-case basis after careful evaluation anddiscussion with the BMS Medical Monitor/Study Director to determinewhether the risk/benefit ratio supports administration of further studytreatment. Upon completion of the additional study treatment period allparticipants enter the safety follow-up period.

Treatment Beyond Progression

Treatment beyond progression is allowed in select participants withinitial RECIST v1.1 or PCGW3 (prostate only) defined PD after discussionand agreement with the BMS Medical Monitor/Study Director that thebenefit/risk assessment favors continued administration of studytreatment (e.g., participants are continuing to experience clinicalbenefit as assessed by the investigator, tolerating treatment, andmeeting other criteria).

Participants are re-consented with an informed consent form (ICF)addendum to continue treatment beyond progression. Treatment beyondprogression requires continued tumor assessments.

Retreatment During Response Follow-Up

Retreatment is allowed in this study with disease progression during theResponse Follow-up period. Participants completing approximately 24weeks of study treatment (or up to a maximum of 48 weeks if applicable)for Part A and approximately two years of study treatment (or up to amaximum of 4 years, if applicable) for Parts B, C, D, and E or less incase of discontinuation due to CR, who enter the Response Follow-upperiod with ongoing disease control (CR, PR, or SD) and without anysignificant toxicity are eligible for retreatment upon subsequentconfirmed disease progression within 12 months of the last dose of studytreatment on a case-by-case basis after careful evaluation anddiscussion with the BMS Medical Monitor/Study Director to determinewhether the risk/benefit ratio supports administration of further studytreatment and the participant continues to meet eligibility criteria fortreatment with study treatment.

Participants meeting criteria for retreatment are treated with theoriginally assigned monotherapy or combination therapy regimen (e.g.,the same dose and dose schedule administered during the first 24 weeks),unless that dose(s) and schedule are subsequently found to exceed thelatest BLRM-RD, in which case the participant is treated with theBLRM-RD. Participants entering this phase follow the proceduralschedule. Samples for PK and pharmacodynamics are collected lessfrequently (at predose of each treatment cycle). During retreatment,pharmacodynamic biomarker samples obtained from blood are collected.

Type of Participant and Target Disease Characteristics

-   -   a) Participants must be at least 18 years old and have        histological or cytological confirmation of metastatic and/or        unresectable colorectal cancer (CRC), head and neck squamous        cell carcinoma (HNSCC), non-small cell lung cancer (NSCLC),        adenocarcinoma of the prostate (PRC), and urothelial carcinoma        (UCC) with measureable disease per RECIST v1.1 or PCGW3        (prostate only) and have at least 1 lesion accessible for biopsy        in addition to the target lesion.    -   b) Presence of at least 1 lesion with measurable disease as        defined by RECIST v1.1 or PCGW3 (prostate only) for solid tumors        for response assessment. Participants with lesions in a        previously irradiated field as the sole site of measurable        disease are permitted to enroll provided the lesion(s) have        demonstrated clear progression and can be measured.    -   c) Participants must have received, and then progressed or been        intolerant to, at least 1 standard treatment regimen in the        advanced or metastatic setting, if such a therapy exists, and        have been considered for all other potentially efficacious        therapies prior to enrollment.    -   d) Participants with prior exposure to therapy with any agent        specifically targeting checkpoint pathway inhibition (such as        anti-PD-1, anti-PD-L1, or anti-CTLA-4) are permitted after a        washout period of any time greater than 4 weeks from the last        treatment.        Tumor Types        a) Colorectal Cancer (CRC)    -   i) Histologically confirmed CRC that is metastatic or recurrent        with documented disease progression.    -   ii) Document microsatellite instability, mismatch repair, KRAS,        and BRAF status if known.    -   iii) Prior therapy requirement: Participants must have received        at least 1, but no more than 3, prior systemic therapies for        metastatic and/or unresectable disease (or have progressed        within 6 months of adjuvant therapy).    -   iv) Participant must have incurable metastatic disease (i.e.,        patients with disease that is potentially curable by surgical        resection are not eligible for treatment).        b) Head and Neck Squamous Cell Carcinoma (HNSCC) (Oral Cavity,        Pharynx, Larynx)    -   i) Histologically confirmed incurable locally advanced,        recurrent, or metastatic HNSCC (oral cavity, pharynx, larynx),        Stage III or IV and not amenable to local therapy with curative        intent (surgery or radiation therapy with or without        chemotherapy).    -   ii) Must have documented HPV status and subtype, particularly        HPV16 and HPV18.    -   iii) Participants must have received and then progressed or have        been intolerant or refractory to at least 1 but no more than 2        prior systemic therapies (e.g., platinum-based chemotherapy)        regimen for the treatment of metastatic or locally advanced        unresectable disease.    -   iv) Prior curative radiation therapy must have been completed at        least 4 weeks prior to study treatment administration. Prior        focal palliative radiotherapy must have been completed at least        2 weeks before study treatment administration.        c) Non-Small Cell Lung Cancer (NSCLC)    -   i) Participants must have histologic or cytologic confirmation        of NSCLC (per the seventh International Association for the        Study of Lung Cancer [IASLC]) with squamous or nonsquamous        histology that is advanced (metastatic and/or unresectable).        -   (1). Participants must have had at least 1, but not more            than 2, prior systemic therapies for NSCLC. Maintenance,            adjuvant, or neoadjuvant (chemotherapy or chemoradiation)            therapy do not count as an additional line of treatment.        -   (2). Participants should have been offered a platinum-based            chemotherapy for NSCLC. The platinum-based chemotherapy may            have been in the adjuvant, neoadjuvant, or chemoradiation            setting. Participants with recurrent/metastatic disease that            has recurred within 6 months of completing such treatment            are considered eligible for study treatment. Prior adjuvant            or neoadjuvant chemotherapy is permitted as long as the last            administration of the prior regimen occurred at least 4            weeks prior to enrollment.        -   (3). Prior definitive chemoradiation for locally advanced            disease is also permitted as long as the last administration            of chemotherapy or radiotherapy (whichever was given last)            occurred at least 4 weeks prior to enrollment.        -   (4). Participants with known EGFR mutations or ALK            rearrangements must have received EGFR or ALK inhibitors,            respectively. EGFR, ALK, KRAS, and ROS1 mutational status            must be documented, if known.            d) Adenocarcinoma of the Prostate (PRC)    -   i) Histologic or cytologic confirmation of adenocarcinoma of the        prostate.    -   ii) Participants have been treated by orchiectomy or are        receiving a luteinizing hormone-releasing hormone analog, and        have a testosterone level≤50 ng/dL.    -   iii) Metastatic disease by any 1 of the following modalities:        computerized tomography (CT), magnetic resonance imaging (MRI),        and bone scan.        e) Urothelial Carcinoma (UCC)    -   i) Histological or cytological evidence of metastatic or        surgically unresectable transitional cell carcinoma of the        urothelium involving the bladder, urethra, ureter, or renal        pelvis.        ICOS.33 IgG1f S267E Dose-Limiting Toxicities (DLTs)

For the purpose of guiding dose escalation, DLTs are defined based onthe incidence, intensity, and duration of AEs for which no clearalternative cause is identified. The DLT period is be 35 days (5 weeks).

In the Preliminary Safety Cohorts, participants who receive 1 dose ofICOS.33 IgG1f S267E and complete, or who discontinue due to a DLT in the4-week DLT period, are considered as DLT-evaluable participants forICOS.33 IgG1f S267E monotherapy.

In Part A, participants who receive 2 doses of ICOS.33 IgG1f S267E andcomplete, or who discontinue due to a DLT in the 5-week DLT period, areconsidered as DLT-evaluable participants for ICOS.33 IgG1f S267Emonotherapy.

In Parts B, C, D and E, participants receiving either 1 dose of ICOS.33IgG1f S267E or 2 doses of either nivolumab or ipilimumab, orparticipants who discontinue due to a DLT in the 5-week combinationtreatment DLT period, are considered as DLT-evaluable participants forcombination treatment. Participants who withdraw from the study duringthe DLT evaluation period or receive less than 2 doses for reasons otherthan a DLT in the monotherapy (Part A) or 1 dose in combination therapy(Parts B, C, D, E), are not considered as DLT-evaluable participants andare not replaced with a new participant at the same dose level.Participants in Part A who are dose delayed during the DLT evaluationperiod for reasons other than a DLT are considered as DLT-evaluableparticipants if they receive at least 2 doses of therapy.

For the purpose of participant management, any AE that meets DLTcriteria, regardless of the cycle in which it occurs, leads todiscontinuation of study treatment. Participants who withdraw from thestudy during the 5-week DLT evaluation period for reasons other than aDLT may be replaced with a new participant at the same dose level. Theincidence of DLT(s) during the 5-week DLT evaluation period is used indose escalation decisions and to define the BLRM-RD. AEs occurring afterthe DLT period are considered for the purposes of defining the BLRM-RDupon agreement between the Sponsor, Medical Monitor/Study Director, andinvestigators.

Participants experiencing a DLT enter the safety follow-up period of thestudy. DLTs occurring after the 4-week DLT observation period for thePreliminary Safety Cohorts or 5-week DLT observation period for Parts A,B, and C are accounted for in determining the maximum administered dose(MAD) for the combination part.

This study will show that the anti-ICOS antibodies as administered aresafe and effective in treating cancer.

Example 19 Combination Effects of Increasing Doses of Anti-ICOS Antibodyon Tumor Growth

The effect of increasing doses of agonistic anti-ICOS antibody, ICOS.33IgG1f S267E, in combination with an anti-PD-1 antibody was assessed ontumor growth inhibition in a mouse model. As shown in FIG. 28, thecombination exhibited reduced efficacy at higher doses, i.e., the “hookeffect,” wherein near-saturating or saturating concentrations of theantibody result in diminished efficacy compared to the efficacy of theantibody at lower concentrations, i.e., concentrations that do notresult in saturation.

Briefly, mice (averaging about 20 mg in weight) with established CT26tumors were treated by either anti-PD-1 monotherapy or in combinationwith ICOS.33 IgG1f S267E. Anti-ICOS dose escalation was started from 0.1mg/kg with three-fold increase to 10 mg/kg (or a maximum dose ofapproximately 200 μg/mouse flat dose). Anti-PD-1 antibody was dosed at10 mg/kg (or a maximum dose of approximately 200 μg/mouse flat dose).Anti-ICOS and anti-PD1 antibody were administered in the same schedule(i.e., every 4 days starting on day 7) following tumor implantation.

As shown in FIG. 28, maximal tumor growth inhibition (TGI) in anti-ICOSand anti-PD1 combination therapy was observed at a lower dose of theanti-ICOS antibody (3 mg/kg) than the maximal dose tested (10 mg/kg),demonstrating a decrease in TGI at doses greater than 3 mg/kg, i.e.,maximal efficacy is achieved at sub-saturating doses.

TABLE 35 Summary of Sequence Listing SEQ ID NO Sequence Name Sequence 1Human ICOS MKSGLWYFFL FCLRIKVLTG EINGSANYEM FIFHNGGVQI 40 (NP_036224.1)LCKYPDIVQQ FKMQLLKGGQ ILCDLTKTKG SGNTVSIKSL 80KFCHSQLSNN SVSFFLYNLD HSHANYYFCN LSIFDPPPFK 120VTLTGGYLHI YESQLCCQLK FWLPIGCAAF VVVCILGCIL 160ICWLTKKKYS SSVHDPNGEY MFMRAVNTAK KSRLTDVTL 199 2 Human ICOS-LMRLGSPGLLF LLFSSLRADT QEKEVRAMVG SDVELSCACP 40 (NP_001269979.1)EGSRFDLNDV YVYWQTSESK TVVTYHIPQN SSLENVDSRY 80RNRALMSPAG MLRGDFSLRL FNVTPQDEQK FHCLVLSQSL 120GFQEVLSVEV TLHVAANFSV PVVSAPHSPS QDELTFTCTS 160INGYPRPNVY WINKTDNSLL DQALQNDTVF LNMRGLYDVV 200SVLRIARTPS VNIGCCIENV LLQQNLTVGS QTGNDIGERD 240KITENPVSTG EKNAATWSIL AVLCLLVVVA VAIGWVCRDR 280CLQHSYAGAW AVSPETELTE SWNLLLLLS 309 3 ParentalEVQLVESGGG LVKPAGSLTL SCVASGFTFS DYFMHWVRQA 40 hamsterPGKGLEWVAV IDTKSFNYAT YYSDLVKGRF TVSRDDSQGM 80 antibody HeavyVYLQMNNLRK EDTATYYCTA TIAVPYYFDY WGQGTMVTVS 120 ChainSATTTAPSVY PLAPACDSTT STTNTVTLGC LVKGYFPEPV 160TVSWNSGALT SGVHTFPSVL HSGLYSLSSS VTVPSSTWPS 200QTVTCNVAHP ASSTKVDKKI VPGDGSGCKP CTCPGPEVSS 240VFIFPPKPKD VLTISLSPKV TCVVVDISQD DPEVQFSWFI 280DGKEVHTAVT QPREEQFNST YRMVSVLPIL HQDWLNGKEF 320KCKVNSPAFP VPIEKTISKR RGQLQVPQVY TMPPPKEQLT 360QSQVSLTCMI KGFYPEDIDV AWQKNGQPEQ SFKNTPPVLD 400TDETYFLYSK LDVKKDDWEK GDTFTCSVVH EALHNHHTEK 440 TLSQRPGK 448 4 ParentalDIQMTQSPSS LPASLGDRVT INCQASQDIS NYLSWYQQKP 40 hamsterGKAPKLLIYY TNLLADGVPS RFSGSGSGRD YSFTISSLES 80 antibody LightEDIGSYYCQQ YYNYRTFGPG TKLEIKRADA KPTVSIFPPS 120 ChainSEQLGTGSAT LVCFVNNFYP KDINVKWKVD GSEKRDGVLQ 160SVTDQDSKDS TYSLSSTLSL TKADYERHNL YTCEVTHKTS 200 TAAIVKTLNR NEC 213 5ICOS.33 IgG1f EVQLVESGGG LVKPGGSLRL SCAASGFTFS DYFMHWVRQA 40 S267E HeavyPGKGLEWVGV IDTKSFNYAT YYSDLVKGRF TISRDDSKNT 80 Chain VariableLYLQMNSLKT EDTAVYYCTA TIAVPYYFDY WGQGTLVTVS 120 Domain S 121 6ICOS.33 IgG1f DIQMTQSPSS LSASVGDRVT ITCQASQDIS NYLSWYQQKP 40 S267E LightGKAPKLLIYY TNLLAEGVPS RFSGSGSGTD FTFTISSLQP 80 Chain VariableEDIATYYCQQ YYNYRTFGPG TKVDIK 106 Domain 7 ICOS.33 IgG1fEVQLVESGGG LVKPGGSLRL SCAASGFTFS DYFMHWVRQA 40 S267E HeavyPGKGLEWVGV IDTKSFNYAT YYSDLVKGRF TISRDDSKNT 80 ChainLYLQMNSLKT EDTAVYYCTA TIAVPYYFDY WGQGTLVTVS 120SASTKGPSVF PLAPSSKSTS GGTAALGCLV KDYFPEPVTV 160SWNSGALTSG VHTFPAVLQS SGLYSLSSVV TVPSSSLGTQ 200TYICNVNHKP SNTKVDKRVE PKSCDKTHTC PPCPAPELLG 240GPSVFLFPPK PKDTLMISRT PEVTCVVVDV EHEDPEVKFN 280WYVDGVEVHN AKTKPREEQY NSTYRVVSVL TVLHQDWLNG 320KEYKCKVSNK ALPAPIEKTI SKAKGQPREP QVYTLPPSRE 360EMTKNQVSLT CLVKGFYPSD IAVEWESNGQ PENNYKTTPP 400VLDSDGSFFL YSKLTVDKSR WQQGNVFSCS VMHEALHNHY 440 TQKSLSLSPG 450 8ICOS.33 IgG1f DIQMTQSPSS LSASVGDRVT ITCQASQDIS NYLSWYQQKP 40 S267E LightGKAPKLLIYY TNLLAEGVPS RFSGSGSGTD FTFTISSLQP 80 ChainEDIATYYCQQ YYNYRTFGPG TKVDIKRTVA APSVFIFPPS 120DEQLKSGTAS VVCLLNNFYP REAKVQWKVD NALQSGNSQE 160SVTEQDSKDS TYSLSSTLTL SKADYEKHKV YACEVTHQGL 200 SSPVTKSFNR GEC 213 9ICOS.33 IgG1f DYFMH 5 S267E CDRH1 10 ICOS.33 IgG1f VIDTKSFNYA TYYSDLVKG19 S267E CDRH2 11 ICOS.33 IgG1f TIAVPYYFDY 10 S267E CDRH3 12ICOS.33 IgG1f QASQDISNYL S 11 S267E CDRL1 13 Parental YTNLLAD 7 hamsterantibody CDRL2 14 ICOS.33 IgG1f YTNLLAE 7 S267E CDRL2 15 ICOS.33 IgG1fQQYYNYRT 8 S267E CDRL3 16 17C4 HeavyMDILCSTLLL LTVPSWVLSQ VTLRESGPAL VKPTQTLTLT 40 Chain VariableCTFSGFSLST SGMCVSWIRQ PPGKALEWLA LIDWDDDKFY 80 DomainSTSLKTRLTI SKDTSKNQVV LTMTNMDPVD TATYYCARMS 120 TPTYYGLDVW GQGTTVTVSS140 17 17C4 Light MRVLAQLLGL LLLCFPGARC DIQMTQSPSS LSASVGDRVT 40Chain Variable ITCRASQGIS SWLAWYQQKP EKAPKSLIYA ASSLQSGVPS 80 DomainRFSGSGSGTD FTLTISSLQP EDFATYYCQQ YNSYPLTFGG 120 GTKVEIK 127 1817C4 CDRH1 TSGMCVS 7 19 17C4 CDRH2 LIDWDDDKFY STSLKT 16 20 17C4 CDRH3MSTPTYYGLD V 11 21 17C4 CDRL1 RASQGISSWL A 11 22 17C4 CDRL2 AASSLQS 7 2317C4 CDRL3 QQYNSYPLT 9 24 9D5 HeavyMDTLCSTLLL LTIPSWVLSQ ITLKESGPTL VKPTQTLTLT 40 Chain VariableCTFSGFSLGT SGLGVGWIRQ PPGKALEWLA FIYWDDDKRY 80 DomainSPSLKSRLTI TKDTSKNQVV LTMTNMDPVD TATYYCAHRR 120 GFFDYWGQGT LVTVSS 136 259D5 Light Chain MRVLAQLLGL LLLCFPGARC DIQMTQSPSS LSASVGDRVT 40 VariableITCRASQGIS SWLAWYQQKP EKAPKSLIYA ASSLQSGVPS 80 DomainRFSGSGSGTD FTLTISSLQP EDFATYYCQQ YNSYPLTFGG 120 GTKVEIK 127 26 9D5 CDRH1TSGLGVG 7 27 9D5 CDRH2 FIYWDDDKRY SPSLKS 16 28 9D5 CDRH3 RRGFFDY 7 299D5 CDRL1 RASQGISSWL A 11 30 9D5 CDRL2 AASSLQS 7 31 9D5 CDRL3 QQYNSYPLT9 32 3E8 Heavy MEFGLTWVFL VALLRGVQCQ VQLVESGGGV VQPGMSLRLS 40Chain Variable CAASGFTFST YGMQWVRQAP GKGLEWVTVI WHDGSHKDYA 80 DomainDSVKGRFTIS RDNSKNTMYL QMNSLRAEDT AVYYCARDRQ 120 TGEGYFDFWG QGTLVTVSS 13933 3E8 Light Chain MRVLAQLLGL LLLCFPGARC DIQMTQSPSS LSASVGDRVT 40Variable ITCRASQGIS SWLAWYQQKP EKAPKSLIYA ASSLQSGVPS 80 DomainRFSGSGSGTD FTLTISSLQP EDFATYYCQQ YNSYPYTFGQ 120 GTKLEIK 127 34 3E8 CDRH1TYGMQ 5 35 3E8 CDRH2 VIWHDGSHKD YADSVKG 17 36 3E8 CDRH3 DRQTGEGYFD F 1137 3E8 CDRL1 RASQGISSWL A 11 38 3E8 CDRL2 AASSLQS 7 39 3E8 CDRL3QQYNSYPYT 9 40 1D7 Heavy MDTLCSTLLL LTIPSWVLSQ ITLKESGPTL VKPTQTLTLT 40Chain Variable CTFSGFSLGS NGLGVGWIRQ PPGKALEWLA LIYWDDDKRY 80 DomainSPSLKSRLTI TKDSSKNQVV LTMTNMDPVD TATYYCAHRN 120 SGFDYWGQGI LVTVSS 136 411D7 Light Chain- MRVLAQLLGL LLLCFPGARC DIQMTQSPSS LSASVGDRVT 40a Variable ITCRASQGFS SWLAWYQQKP EKAPKSLIYA ASSLQSGVPS 80 DomainRFSGSGSGTD FTLTISSLQP EDFATYYCQQ YNSYPYTFGQ 120 GTKLEIK 127 42 1D7 CDRH1SNGLGVG 7 43 1D7 CDRH2 LIYWDDDKRY SPSLKS 16 44 1D7 CDRH3 RNSGFDY 7 451D7 CDRL1-a RASQGFSSWL A 11 46 1D7 CDRL2-a AASSLQS 7 47 1D7 CDRL3-aQQYNSYPYT 9 48 1D7 Light Chain-MRVLAQLLGL LLLCFPGARC DIQMTQSPSS LSASVGDRVT 40 b VariableITCRASQGIS SWLAWYQQKP EKAPKSLIYA ASSLQSGVPS 80 DomainRFSGSGSGTD FTLTISSLQP EDFATYYCQQ YNSYPLTFGG 120 GTKVEIK 127 491D7 CDRL1-b RASQGISSWL A 11 50 1D7 CDRL2-b AASSLQS 7 51 1D7 CDRL3-bQQYNSYPLT 9 52 huIgG1f Heavy ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS40 Chain Constant WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80 DomainYICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGG 120PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW 160YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPG 329 53huIgG1f S267E ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40(“SE”) Heavy WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80Chain Constant YICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGG 120 DomainPSVFLFPPKP KDTLMISRTP EVTCVVVDVE HEDPEVKFNW 160YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPG 329 54 huIgG1fASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 S267E/L328FWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80 (“SELF”) HeavyYICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGG 120 Chain ConstantPSVFLFPPKP KDTLMISRTP EVTCVVVDVE HEDPEVKFNW 160 DomainYVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200EYKCKVSNKA FPAPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPG 329 55huIgG1f P238D ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 Heavy ChainWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80 ConstantYICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGG 120 DomainDSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW 160YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPG 329 56 huIgG1fASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 P238D/P271GWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80 (“V4”) HeavyYICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGG 120 Chain ConstantDSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDGEVKFNW 160 DomainYVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPG 329 57 huIgG1fASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 P238D/P271GWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80 (“V4”) D270EYICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGG 120 Heavy ChainDSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEEGEVKFNW 160 ConstantYVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200 DomainEYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPG 329 58 huIgG1fASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 E233D/P238D/P271G/WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80 A330RYICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPDLLGG 120 (“V7”) HeavyDSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDGEVKFNW 160 Chain ConstantYVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200 DomainEYKCKVSNKA LPRPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPG 329 59 huIgG1fASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 G237D/P238D/WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80 H268D//P271GYICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGD 120 (“V8”) HeavyDSVFLFPPKP KDTLMISRTP EVTCVVVDVS DEDGEVKFNW 160 Chain ConstantYVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200 DomainEYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPG 329 60 huIgG1fASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 G237D/P238D/P271G/WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80 A330RYICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGD 120 (“V9”) HeavyDSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDGEVKFNW 160 Chain ConstantYVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200 DomainEYKCKVSNKA LPRPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPG 329 61 huIgG1fASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 G237D/P238D/P271G/WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80 A330RYICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGD 120 (“V9”) D270EDSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEEGEVKFNW 160 Heavy ChainYVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200 ConstantEYKCKVSNKA LPRPIEKTIS KAKGQPREPQ VYTLPPSREE 240 DomainMTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPG 329 62 huIgG1fASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 G237D/P238D/WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80 H268D/P271G/YICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGD 120 A330R (“V11”)DSVFLFPPKP KDTLMISRTP EVTCVVVDVS DEDGEVKFNW 160 Heavy ChainYVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200 ConstantEYKCKVSNKA LPRPIEKTIS KAKGQPREPQ VYTLPPSREE 240 DomainMTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPG 329 63 huIgG1fASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 E233D/G237D/P238D/WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80 H268D/P271G/YICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPDLLGD 120 A330RDSVFLFPPKP KDTLMISRTP EVTCVVVDVS DEDGEVKFNW 160 (“V12”) HeavyYVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200 Chain ConstantEYKCKVSNKA LPRPIEKTIS KAKGQPREPQ VYTLPPSREE 240 DomainMTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPG 329 64huKappa Light RTVAAPSVFI FPPSDEQLKS GTASVVCLLN NFYPREAKVQ 40Chain Constant WKVDNALQSG NSQESVTEQD SKDSTYSLSS TLTLSKADYE 80 DomainKHKVYACEVT HQGLSSPVTK SFNRGEC 107 65 Signal Sequence MRAWIFFLLC LAGRALA17 66 IgG1 C-terminal VDKRV 5 CH1 (same for IgG3 (17-15-15-15), igG3 (17- 15-15), IgG3 (17-15), IgG3 (15-15-15), IgG3(15), and IgG4 67 IgG1 upper EPKSCDKTHT 10 hinge 68 IgG1 middle CPPCP 5hinge 69 IgG1 lower APELLGG 7 hinge (same for IgG3 (17-15-15-15), IgG3 (17- 15-15), IgG3 (17-15), IgG3 (15-15-15), IgG3(15), and IgG4) 70 IgG2 C-terminal VDKTV 5 CH1 71 IgG2 middle CCVECPPCP9 hinge 72 IgG2 lower APPVAG 6 hinge 73 IgG3 (17-15-15- ELKTPLGDTT HT 1215) upper hinge (same for IgG3 (17-15-15) and IgG3 (17-15)) 74IgG3 (17-15-15- CPRCPEPKSC DTPPPCPRCP EPKSCDTPPP CPRCPEPKSC 4015) middle DTPPPCPRCP 50 hinge 75 IgG3 (17-15-15)CPRCPEPKSC DTPPPCPRCP EPKSCDTPPP CPRCP 35 middle hinge 76 IgG3 (17-15)CPRCPEPKSC DTPPPCPRCP 20 middle hinge 77 IgG3 (15-15-15) EPKS 4upper hinge (same for IgG3(15)) 78 IgG3 (15-15-15)CDTPPPCPRC PEPKSCDTPP PCPRCPEPKS CDTPPPCPRC 40 middle hinge P 41 79IgG3 (15) CDTPPPCPRC P 11 middle hinge 80 IgG4 upper ESKYGPP 7 hinge 81IgG4 middle CPSCP 5 hinge 82 IgG4 lower APEFLGG 7 hinge 83 WildtypeASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 human IgG1WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80 CH1 YICNVNHKPS NTKVDKKV98 84 Wildtype ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40 human IgG2WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80 CH1 YTCNVDHKPS NTKVDKTV98 85 Wildtype PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW 40 human IgG1YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 80 CH2EYKCKVSNKA LPAPIEKTIS KAK 103 86 Human IgG1PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW 40 CH2 withYVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 80 A330S/P331SEYKCKVSNKA LPSSIEKTIS KAK 103 87 WildtypeGQPREPQVYT LPPSREEMTK NQVSLTCLVK GFYPSDIAVE 40 human IgG1WESNGQPENN YKTTPPVLDS DGSFFLYSKL TVDKSRWQQG 80 CH3NVFSCSVMHE ALHNHYTQKS LSLSPG 106 88 IgG1-IgG2-IgG1fASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKKVER KCCVECPPCP APELLGGPSV 120FLFPPKPKDT LMISRTPEVT CVVVDVSHED PEVKFNWYVD 160GVEVHNAKTK PREEQYNSTY RVVSVLTVLH QDWLNGKEYK 200CKVSNKALPA PIEKTISKAK GQPREPQVYT LPPSREEMTK 240NQVSLTCLVK GFYPSDIAVE WESNGQPENN YKTTPPVLDS 280DGSFFLYSKL TVDKSRWQQG NVFSCSVMHE ALHNHYTQKS 320 LSLSPG 326 89IgG1-IgG2CS- ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 IgG1fWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKKVER KSCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVKFNWYVDG 160VEVHNAKTKP REEQYNSTYR VVSVLTVLHQ DWLNGKEYKC 200KVSNKALPAP IEKTISKAKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPVLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPG 325 90 IgG1-IgG2-ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 IgG1.1fWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKKVER KCCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVKFNWYVDG 160VEVHNAKTKP REEQYNSTYR VVSVLTVLHQ DWLNGKEYKC 200KVSNKALPSS IEKTISKAKG QPREPQVYTL PPSRREMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPVLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPG 325 91IgG1-IgG2CS- ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 IgG1.1fWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKKVER KSCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVKFNWYVDG 160VEVHNAKTKP REEQYNSTYR VVSVLTVLHQ DWLNGKEYKC 200KVSNKALPSS IEKTISKAKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPVLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPG 325 92 IgG1-IgG2-ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 1gG1f2WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKKVER KCCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVKFNWYVDG 160VEVHNAKTKP REEQYNSTYR VVSVLTVLHQ DWLNGKEYKC 200KVSNKALPAP IEKTISKAKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPVLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPG 325 93 IgG1-ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 IgG2(C219S)-WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80 IgG1f2YICNVNHKPS NTKVDKKVER KSCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVKFNWYVDG 160VEVHNAKTKP REEQYNSTYR VVSVLTVLHQ DWLNGKEYKC 200KVSNKALPAP IEKTISKAKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPVLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPG 325 94 IgG2-IgG1f2ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KCCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVKFNWYVDG 160VEVHNAKTKP REEQYNSTYR VVSVLTVLHQ DWLNGKEYKC 200KVSNKALPAP IEKTISKAKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPVLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPG 325 95IgG2(C219S)- ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40 IgG1f2WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVKFNWYVDG 160VEVHNAKTKP REEQYNSTYR VVSVLTVLHQ DWLNGKEYKC 200KVSNKALPAP IEKTISKAKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPVLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPG 325 96WT human IgG2 ERKCCVECPP CPAPPVAG 18 hinge 97 Human IgG2ERKSCVECPP CPAPPVAG 18 hinge with C219S 98 IgG2/IgG1 hingeERKCCVECPP CPAPELLGG 19 99 IgG2 ERKSCVECPP CPAPELLGG 19 (C219S)/IgG1hinge 100 Wild type EPKSCDKTHT CPPCPAPELL GG 22 human IgG1 hinge 101IgG1.1 Hinge EPKSCDKTHT CPPCPAPEAE GA 22 (L234A/L235E/G237A) 102Wildtype PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVQFNW 40 human IgG2YVDGVEVHNA KTKPREEQFN STFRVVSVLT VVHQDWLNGK 80 CH2EYKCKVSNKG LPAPIEKTIS KTK 103 103 WildtypeGQPREPQVYT LPPSREEMTK NQVSLTCLVK GFYPSDIAVE 40 human IgG2WESNGQPENN YKTTPPMLDS DGSFFLYSKL TVDKSRWQQG 80 CH3NVFSCSVMHE ALHNHYTQKS LSLSPGK 107 104 IgG1f with C-ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 terminal KWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGG 120PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW 160YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPGK 330 105IgG2.3 ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVQFNWYVDG 160VEVHNAKTKP REEQFNSTFR VVSVLTVVHQ DWLNGKEYKC 200KVSNKGLPAP IEKTISKTKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPMLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 106IgG2.3G1-AY ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCVECPPCP APELLGGPSV 120FLFPPKPKDT LMISRTPEVT CVVVDVSHED PEVKFNWYVD 160GVEVHNAKTK PREEQYNSTY RVVSVLTVLH QDWLNGKEYK 200CKVSNKALPA PIEKTISKAK GQPREPQVYT LPPSREEMTK 240NQVSLTCLVK GFYPSDIAVE WESNGQPENN YKTTPPVLDS 280DGSFFLYSKL TVDKSRWQQG NVFSCSVMHE ALHNHYTQKS 320 LSLSPGK 327 107IgG2.3G1-KH ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVKFNWYVDG 160VEVHNAKTKP REEQYNSTYR VVSVLTVLHQ DWLNGKEYKC 200KVSNKALPAP IEKTISKAKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPVLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 108 IgG2.5ASTKGPSVFP LAPSSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KCCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVQFNWYVDG 160VEVHNAKTKP REEQFNSTFR VVSVLTVVHQ DWLNGKEYKC 200KVSNKGLPAP IEKTISKTKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPMLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 109 IgG1.1fASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPEAEGA 120PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW 160YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200EYKCKVSNKA LPSSIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPGK 330 110IgG2.3G1.1f-KH ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVKFNWYVDG 160VEVHNAKTKP REEQYNSTYR VVSVLTVLHQ DWLNGKEYKC 200KVSNKALPSS IEKTISKAKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPVLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 111IgG1-deltaTHT ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKRVEP KSCDKCPPCP APELLGGPSV 120FLFPPKPKDT LMISRTPEVT CVVVDVSHED PEVKFNWYVD 160GVEVHNAKTK PREEQYNSTY RVVSVLTVLH QDWLNGKEYK 200CKVSNKALPA PIEKTISKAK GQPREPQVYT LPPSREEMTK 240NQVSLTCLVK GFYPSDIAVE WESNGQPENN YKTTPPVLDS 280DGSFFLYSKL TVDKSRWQQG NVFSCSVMHE ALHNHYTQKS 320 LSLSPGK 327 112IgG2.3-plusTHT ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCVETHTCP PCPAPPVAGP 120SVFLFPPKPK DTLMISRTPE VTCVVVDVSH EDPEVQFNWY 160VDGVEVHNAK TKPREEQFNS TFRVVSVLTV VHQDWLNGKE 200YKCKVSNKGL PAPIEKTISK TKGQPREPQV YTLPPSREEM 240TKNQVSLTCL VKGFYPSDIA VEWESNGQPE NNYKTTPPML 280DSDGSFFLYS KLTVDKSRWQ QGNVFSCSVM HEALHNHYTQ 320 KSLSLSPGK 329 113IgG2.3-plusGGG ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCVEGGGCP PCPAPPVAGP 120SVFLFPPKPK DTLMISRTPE VTCVVVDVSH EDPEVQFNWY 160VDGVEVHNAK TKPREEQFNS TFRVVSVLTV VHQDWLNGKE 200YKCKVSNKGL PAPIEKTISK TKGQPREPQV YTLPPSREEM 240TKNQVSLTCL VKGFYPSDIA VEWESNGQPE NNYKTTPPML 280DSDGSFFLYS KLTVDKSRWQ QGNVFSCSVM HEALHNHYTQ 320 KSLSLSPGK 329 114IgG2.5G1.1f-KH ASTKGPSVFP LAPSSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KCCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVKFNWYVDG 160VEVHNAKTKP REEQYNSTYR VVSVLTVLHQ DWLNGKEYKC 200KVSNKALPSS IEKTISKAKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPVLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 115IgG2.5G1-AY ASTKGPSVFP LAPSSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KCCVECPPCP APELLGGPSV 120FLFPPKPKDT LMISRTPEVT CVVVDVSHED PEVKFNWYVD 160GVEVHNAKTK PREEQYNSTY RVVSVLTVLH QDWLNGKEYK 200CKVSNKALPA PIEKTISKAK GQPREPQVYT LPPSREEMTK 240NQVSLTCLVK GFYPSDIAVE WESNGQPENN YKTTPPVLDS 280DGSFFLYSKL TVDKSRWQQG NVFSCSVMHE ALHNHYTQKS 320 LSLSPGK 327 116IgG2.5G1-KH ASTKGPSVFP LAPSSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KCCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVKFNWYVDG 160VEVHNAKTKP REEQYNSTYR VVSVLTVLHQ DWLNGKEYKC 200KVSNKALPAP IEKTISKAKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPVLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 117IgG2.5-plusTHT ASTKGPSVFP LAPSSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KCCVETHTCP PCPAPPVAGP 120SVFLFPPKPK DTLMISRTPE VTCVVVDVSH EDPEVQFNWY 160VDGVEVHNAK TKPREEQFNS TFRVVSVLTV VHQDWLNGKE 200YKCKVSNKGL PAPIEKTISK TKGQPREPQV YTLPPSREEM 240TKNQVSLTCL VKGFYPSDIA VEWESNGQPE NNYKTTPPML 280DSDGSFFLYS KLTVDKSRWQ QGNVFSCSVM HEALHNHYTQ 320 KSLSLSPGK 329 118IgG1-G2.3G1-AY ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKRVER KSCVECPPCP APELLGGPSV 120FLFPPKPKDT LMISRTPEVT CVVVDVSHED PEVKFNWYVD 160GVEVHNAKTK PREEQYNSTY RVVSVLTVLH QDWLNGKEYK 200CKVSNKALPA PIEKTISKAK GQPREPQVYT LPPSREEMTK 240NQVSLTCLVK GFYPSDIAVE WESNGQPENN YKTTPPVLDS 280DGSFFLYSKL TVDKSRWQQG NVFSCSVMHE ALHNHYTQKS 320 LSLSPGK 327 119IgG1-G2.3G1-KH ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKRVER KSCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVKFNWYVDG 160VEVHNAKTKP REEQYNSTYR VVSVLTVLHQ DWLNGKEYKC 200KVSNKALPAP IEKTISKAKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPVLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 120G2-G1-G1-G1 ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCDKTHTCP PCPAPELLGG 120PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW 160YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPGK 330 121G2.5-G1-G1-G1 ASTKGPSVFP LAPSSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCDKTHTCP PCPAPELLGG 120PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW 160YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPGK 330 122G1-G2.3-G2-G2 ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKRVEP KSCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVQFNWYVDG 160VEVHNAKTKP REEQFNSTFR VVSVLTVVHQ DWLNGKEYKC 200KVSNKGLPAP IEKTISKTKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPMLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 123G1-KRGEGSSNLF ASTKGPSVFP LAPSSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGG 120PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW 160YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPGK 330 124G1-KRGEGS ASTKGPSVFP LAPSSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGG 120PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW 160YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPGK 330 125G1-SNLF ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGG 120PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW 160YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPGK 330 126IgG1-ITNDRTPR ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YTCNVDHKPS NTKVDKTVER KSCDKTHTCP PCPAPELLGG 120PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW 160YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPGK 330 127G1-SNLFPR ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YICNVNHKPS NTKVDKRVER KSCDKTHTCP PCPAPELLGG 120PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW 160YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPG 329 128G2-RKEGSGNSFL ASTKGPSVFP LAPCSKSTSG GTAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YTCNVDHKPS NTKVDKTVER KSCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVQFNWYVDG 160VEVHNAKTKP REEQFNSTFR VVSVLTVVHQ DWLNGKEYKC 200KVSNKGLPAP IEKTISKTKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPMLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 129 G2-RKEGSGASTKGPSVFP LAPCSKSTSG GTAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVQFNWYVDG 160VEVHNAKTKP REEQFNSTFR VVSVLTVVHQ DWLNGKEYKC 200KVSNKGLPAP IEKTISKTKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPMLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 130 G2-NSFLASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YTCNVDHKPS NTKVDKTVER KSCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVQFNWYVDG 160VEVHNAKTKP REEQFNSTFR VVSVLTVVHQ DWLNGKEYKC 200KVSNKGLPAP IEKTISKTKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPMLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 131IgG2-TIDNTRRP ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YICNVNHKPS NTKVDKRVEP KSCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVQFNWYVDG 160VEVHNAKTKP REEQFNSTFR VVSVLTVVHQ DWLNGKEYKC 200KVSNKGLPAP IEKTISKTKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPMLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 132 G2-NSFLRPASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YTCNVDHKPS NTKVDKTVEP KSCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVQFNWYVDG 160VEVHNAKTKP REEQFNSTFR VVSVLTVVHQ DWLNGKEYKC 200KVSNKGLPAP IEKTISKTKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPMLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 133G1-G1-G2-G1- ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 AYWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGG 120PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVQFNW 160YVDGVEVHNA KTKPREEQFN STFRVVSVLT VVHQDWLNGK 200EYKCKVSNKG LPAPIEKTIS KTKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPGK 330 134G1-G1-G2-G1- ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 KHWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPPVAGP 120SVFLFPPKPK DTLMISRTPE VTCVVVDVSH EDPEVQFNWY 160VDGVEVHNAK TKPREEQFNS TFRVVSVLTV VHQDWLNGKE 200YKCKVSNKGL PAPIEKTISK TKGQPREPQV YTLPPSREEM 240TKNQVSLTCL VKGFYPSDIA VEWESNGQPE NNYKTTPPVL 280DSDGSFFLYS KLTVDKSRWQ QGNVFSCSVM HEALHNHYTQ 320 KSLSLSPGK 329 135G2-G2.3-G1-G2- ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40 KHWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVKFNWYVDG 160VEVHNAKTKP REEQYNSTYR VVSVLTVLHQ DWLNGKEYKC 200KVSNKALPAP IEKTISKAKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPMLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 136G2.5-G2.3-G1- ASTKGPSVFP LAPSSRSTSE STAALGCLVK DYFPEPVTVS 40 G2-KHWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVKFNWYVDG 160VEVHNAKTKP REEQYNSTYR VVSVLTVLHQ DWLNGKEYKC 200KVSNKALPAP IEKTISKAKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPMLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 137G2-G2.3-G1-G2- ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40 AYWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCVECPPCP APELLGGPSV 120FLFPPKPKDT LMISRTPEVT CVVVDVSHED PEVKFNWYVD 160GVEVHNAKTK PREEQYNSTY RVVSVLTVLH QDWLNGKEYK 200CKVSNKALPA PIEKTISKAK GQPREPQVYT LPPSREEMTK 240NQVSLTCLVK GFYPSDIAVE WESNGQPENN YKTTPPMLDS 280DGSFFLYSKL TVDKSRWQQG NVFSCSVMHE ALHNHYTQKS 320 LSLSPG 326 138G2.5-G2.3-G1- ASTKGPSVFP LAPSSRSTSE STAALGCLVK DYFPEPVTVS 40 G2-AYWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCVECPPCP APELLGGPSV 120FLFPPKPKDT LMISRTPEVT CVVVDVSHED PEVKFNWYVD 160GVEVHNAKTK PREEQYNSTY RVVSVLTVLH QDWLNGKEYK 200CKVSNKALPA PIEKTISKAK GQPREPQVYT LPPSREEMTK 240NQVSLTCLVK GFYPSDIAVE WESNGQPENN YKTTPPMLDS 280DGSFFLYSKL TVDKSRWQQG NVFSCSVMHE ALHNHYTQKS 320 LSLSPGK 327 139G1-G2.3-G1-G1- ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 KHWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKRVEP KSCVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVKFNWYVDG 160VEVHNAKTKP REEQYNSTYR VVSVLTVLHQ DWLNGKEYKC 200KVSNKALPAP IEKTISKAKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPVLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 140G2-G1-G2-G2- ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40 AYWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCDKTHTCP PCPAPELLGG 120PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVQFNW 160YVDGVEVHNA KTKPREEQFN STFRVVSVLT VVHQDWLNGK 200EYKCKVSNKG LPAPIEKTIS KTKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPM 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPGK 330 141G2.5-G1-G2-G2- ASTKGPSVFP LAPSSRSTSE STAALGCLVK DYFPEPVTVS 40 AYWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCDKTHTCP PCPAPELLGG 120PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVQFNW 160YVDGVEVHNA KTKPREEQFN STFRVVSVLT VVHQDWLNGK 200EYKCKVSNKG LPAPIEKTIS KTKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPM 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPGK 330 142G1-G2-G1-G1- ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 AYWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKRVEP KSCVECPPCP APELLGGPSV 120FLFPPKPKDT LMISRTPEVT CVVVDVSHED PEVKFNWYVD 160GVEVHNAKTK PREEQYNSTY RVVSVLTVLH QDWLNGKEYK 200CKVSNKALPA PIEKTISKAK GQPREPQVYT LPPSREEMTK 240NQVSLTCLVK GFYPSDIAVE WESNGQPENN YKTTPPVLDS 280DGSFFLYSKL TVDKSRWQQG NVFSCSVMHE ALHNHYTQKS 320 LSLSPGK 327 143G2-G1-G2-G2- ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40 KHWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCDKTHTCP PCPAPPVAGP 120SVFLFPPKPK DTLMISRTPE VTCVVVDVSH EDPEVQFNWY 160VDGVEVHNAK TKPREEQFNS TFRVVSVLTV VHQDWLNGKE 200YKCKVSNKGL PAPIEKTISK TKGQPREPQV YTLPPSREEM 240TKNQVSLTCL VKGFYPSDIA VEWESNGQPE NNYKTTPPML 280DSDGSFFLYS KLTVDKSRWQ QGNVFSCSVM HEALHNHYTQ 320 KSLSLSPG 328 144G2.5-G1-G2-G2- ASTKGPSVFP LAPSSRSTSE STAALGCLVK DYFPEPVTVS 40 KHWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCDKTHTCP PCPAPPVAGP 120SVFLFPPKPK DTLMISRTPE VTCVVVDVSH EDPEVQFNWY 160VDGVEVHNAK TKPREEQFNS TFRVVSVLTV VHQDWLNGKE 200YKCKVSNKGL PAPIEKTISK TKGQPREPQV YTLPPSREEM 240TKNQVSLTCL VKGFYPSDIA VEWESNGQPE NNYKTTPPML 280DSDGSFFLYS KLTVDKSRWQ QGNVFSCSVM HEALHNHYTQ 320 KSLSLSPGK 329 145IgG1-deltaHinge ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKRVEP KCPPCPAPEL LGGPSVFLFP 120PKPKDTLMIS RTPEVTCVVV DVSHEDPEVK FNWYVDGVEV 160HNAKTKPREE QYNSTYRVVS VLTVLHQDWL NGKEYKCKVS 200NKALPAPIEK TISKAKGQPR EPQVYTLPPS REEMTKNQVS 240LTCLVKGFYP SDIAVEWESN GQPENNYKTT PPVLDSDGSF 280FLYSKLTVDK SRWQQGNVFS CSVMHEALHN HYTQKSLSLS 320 PGK 323 146IgG2-deltaHinge ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KCPPCPAPPV AGPSVFLFPP 120KPKDTLMISR TPEVTCVVVD VSHEDPEVQF NWYVDGVEVH 160NAKTKPREEQ FNSTFRVVSV LTVVHQDWLN GKEYKCKVSN 200KGLPAPIEKT ISKTKGQPRE PQVYTLPPSR EEMTKNQVSL 240TCLVKGFYPS DIAVEWESNG QPENNYKTTP PMLDSDGSFF 280LYSKLTVDKS RWQQGNVFSC SVMHEALHNH YTQKSLSLSP 320 GK 322 147 IgG2.5-ASTKGPSVFP LAPSSRSTSE STAALGCLVK DYFPEPVTVS 40 deltaHingeWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KCPPCPAPPV AGPSVFLFPP 120KPKDTLMISR TPEVTCVVVD VSHEDPEVQF NWYVDGVEVH 160NAKTKPREEQ FNSTFRVVSV LTVVHQDWLN GKEYKCKVSN 200KGLPAPIEKT ISKTKGQPRE PQVYTLPPSR EEMTKNQVSL 240TCLVKGFYPS DIAVEWESNG QPENNYKTTP PMLDSDGSFF 280LYSKLTVDKS RWQQGNVFSC SVMHEALHNH YTQKSLSLSP 320 GK 322 148IgG1-deltaG237 ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGP 120SVFLFPPKPK DTLMISRTPE VTCVVVDVSH EDPEVKFNWY 160VDGVEVHNAK TKPREEQYNS TYRVVSVLTV LHQDWLNGKE 200YKCKVSNKAL PAPIEKTISK AKGQPREPQV YTLPPSREEM 240TKNQVSLTCL VKGFYPSDIA VEWESNGQPE NNYKTTPPVL 280DSDGSFFLYS KLTVDKSRWQ QGNVFSCSVM HEALHNHYTQ 320 KSLSLSPG 328 149IgG2-plusG237 ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSCVECPPCP APPVAGGPSV 120FLFPPKPKDT LMISRTPEVT CVVVDVSHED PEVQFNWYVD 160GVEVHNAKTK PREEQFNSTF RVVSVLTVVH QDWLNGKEYK 200CKVSNKGLPA PIEKTISKTK GQPREPQVYT LPPSREEMTK 240NQVSLTCLVK GFYPSDIAVE WESNGQPENN YKTTPPMLDS 280DGSFFLYSKL TVDKSRWQQG NVFSCSVMHE ALHNHYTQKS 320 LSLSPGK 327 150 IgG2.4ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KCSVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVQFNWYVDG 160VEVHNAKTKP REEQFNSTFR VVSVLTVVHQ DWLNGKEYKC 200KVSNKGLPAP IEKTISKTKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPMLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 151 IgG2.3/4ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KSSVECPPCP APPVAGPSVF 120LFPPKPKDTL MISRTPEVTC VVVDVSHEDP EVQFNWYVDG 160VEVHNAKTKP REEQFNSTFR VVSVLTVVHQ DWLNGKEYKC 200KVSNKGLPAP IEKTISKTKG QPREPQVYTL PPSREEMTKN 240QVSLTCLVKG FYPSDIAVEW ESNGQPENNY KTTPPMLDSD 280GSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL 320 SLSPGK 326 152Hinge IgG2 ERKCSVECPP CPAPPVAG 18 C220S 153 IgG2/IgG1ERKCSVECPP CPAPELLGG 19 hybrid hinge C220S 154 Wildtype IgG2ERKCCVECPP CPAP 14 hinge portion 155 IgG2 hinge ERKSCVECPP CPAP 14portion C219S 156 IgG2 hinge ERKCSVECPP CPAP 14 portion C220S 157IgG2 hinge ERKXCVECPP CPAP 14 portion C219X 158 IgG2 hingeERKCXVECPP CPAP 14 portion C220X 159 IgG2 CH1 + IgG2ASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS 40 hinge (wildtype)WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSNFGTQT 80YTCNVDHKPS NTKVDKTVER KCCVECPPCP APPVAG 116 160 IgG2 with C219XERKXCVECPP CPAPPVAG 18 161 IgG2 with C220X ERKCXVECPP CPAPPVAG 18 162IgG2/IgG1 ERKXCVECPP CPAPELLGG 19 hybrid with C219X 163 IgG2/IgG1ERKCXVECPP CPAPELLGG 19 hybrid with C220X 164 IgG2/IgG1ERKCCVECPP CPAPELLG 18 hybrid deltaG 165 IgG2/IgG1 ERKSCVECPP CPAPELLG18 hybrid with C219S deltaG 166 IgG2/IgG1 ERKCSVECPP CPAPELLG 18hybrid with C220S deltaG 167 IgG2/IgG1 ERKXCVECPP CPAPELLG 18hybrid with C219X deltaG 168 IgG2/IgG1 ERKCXVECPP CPAPELLG 18hybrid with C220X deltaG 169 IgG2 hinge PVAG 4 portion 170 IgG1 hingeSCDKTHT 7 portion 171 IgG1 hinge ELLG 4 portion 1 172 IgG1 hinge ELLGG 5portion 2 173 Mature huICOS EINGSANYEM FIFHNGGVQI LCKYPDIVQQ FKMQLLKGGQ40 Extracellular ILCDLTKTKG SGNTVSIKSL KFCHSQLSNN SVSFFLYNLD 80Domain (21- HSHANYYFCN LSIFDPPPFK VTLTGGYLHI YESQ 114 134 ofNP_036224.1) 174 3E8 HeavyATG GAG TTT GGG CTG ACC TGG GTT TTC CTC GTT GCT 36 Chain VariableCTT TTA AGA GGT GTC CAG TGT CAG GTG CAG CTG GTG 72 DomainGAG TCT GGG GGA GGC GTG GTC CAG CCT GGG ATG TCC 108 NucleotideCTG AGA CTC TCC TGT GCA GCG TCT GGA TTC ACC TTC 144 SequenceAGT ACC TAT GGC ATG CAG TGG GTC CGC CAG GCT CCA 180GGC AAG GGG CTG GAG TGG GTG ACA GTT ATA TGG CAT 216GAT GGA AGT CAT AAA GAC TAT GCA GAC TCC GTG AAG 252GGC CGA TTC ACC ATC TCC AGA GAC AAT TCC AAG AAC 288ACG ATG TAT CTG CAA ATG AAC AGC CTG AGA GCC GAG 324GAC ACG GCT GTG TAT TAC TGT GCG AGA GAT CGG CAA 360ACT GGG GAG GGC TAC TTT GAC TTC TGG GGC CAG GGA 396ACC CTG GTC ACC GTC TCC TCA 417 175 3E8 Light ChainATG AGG GTC CTC GCT CAG CTC CTG GGG CTC CTG CTG 36 VariableCTC TGT TTC CCA GGT GCC AGA TGT GAC ATC CAG ATG 72 DomainACC CAG TCT CCA TCC TCA CTG TCT GCA TCT GTA GGA 108 NucleotideGAC AGA GTC ACC ATC ACT TGT CGG GCG AGT CAG GGT 144 SequenceATT AGC AGC TGG TTA GCC TGG TAT CAG CAG AAA CCA 180GAG AAA GCC CCT AAG TCC CTG ATC TAT GCT GCA TCC 216AGT TTG CAA AGT GGG GTC CCA TCA AGG TTC AGC GGC 252AGT GGA TCT GGG ACA GAT TTC ACT CTC ACC ATC AGC 288AGC CTG CAG CCT GAA GAT TTT GCA ACT TAT TAC TGC 324CAA CAG TAT AAT AGT TAC CCG TAC ACT TTT GGC CAG 360GGG ACC AAG CTG GAG ATC AAA 381 176 17C4 HeavyATG GAC ATA CTT TGT TCC ACG CTC CTG CTA CTG ACT 36 Chain VariableGTC CCG TCC TGG GTC TTA TCC CAG GTC ACC TTG AGG 72 DomainGAG TCT GGT CCT GCG CTG GTG AAA CCC ACA CAG ACC 108 NucleotideCTC ACA CTG ACC TGC ACC TTC TCT GGG TTC TCA CTC 144 SequenceAGC ACT AGT GGA ATG TGT GTG AGC TGG ATC CGT CAG 180CCC CCA GGG AAG GCC CTG GAG TGG CTT GCA CTC ATT 216GAT TGG GAT GAT GAT AAA TTC TAC AGC ACA TCT CTG 252AAG ACC AGG CTC ACC ATC TCC AAG GAC ACC TCC AAA 288AAC CAG GTG GTC CTT ACA ATG ACC AAC ATG GAC CCT 324GTG GAC ACA GCC ACG TAT TAC TGT GCA CGG ATG TCA 360ACA CCT ACC TAC TAC GGT TTG GAC GTC TGG GGC CAA 396GGG ACC ACG GTC ACC GTC TCC TCA 420 177 17C4 LightATG AGG GTC CTC GCT CAG CTC CTG GGG CTC CTG CTG 36 Chain VariableCTC TGT TTC CCA GGT GCC AGA TGT GAC ATC CAG ATG 72 DomainACC CAG TCT CCA TCC TCA CTG TCT GCA TCT GTA GGA 108 NucleotideGAC AGA GTC ACC ATC ACT TGT CGG GCG AGT CAG GGT 144 SequenceATT AGC AGC TGG TTA GCC TGG TAT CAG CAG AAA CCA 180GAG AAA GCC CCT AAG TCC CTG ATC TAT GCT GCA TCC 216AGT TTG CAA AGT GGG GTC CCA TCA AGG TTC AGC GGC 252AGT GGA TCT GGG ACA GAT TTC ACT CTC ACC ATC AGC 288AGC CTG CAG CCT GAA GAT TTT GCA ACT TAT TAC TGC 324CAA CAG TAT AAT AGT TAC CCT CTC ACT TTC GGC GGA 360GGG ACC AAG GTG GAG ATC AAA 381 178 1D7 HeavyATG GAC ACA CTT TGC TCC ACG CTC CTG CTG CTG ACC 36 Chain VariableATC CCT TCA TGG GTC TTG TCC CAG ATC ACC TTG AAG 72 DomainGAG TCT GGT CCT ACG CTG GTG AAA CCC ACA CAG ACC 108 NucleotideCTC ACG CTG ACC TGC ACC TTC TCT GGG TTC TCA CTC 144 SequenceGGC TCT AAT GGA CTG GGT GTG GGC TGG ATC CGT CAG 180CCC CCA GGA AAG GCC CTG GAG TGG CTT GCA CTC ATT 216TAT TGG GAT GAT GAT AAG CGC TAC AGT CCA TCT CTG 252AAG AGC AGG CTC ACC ATC ACC AAG GAC TCC TCC AAA 288AAC CAG GTG GTC CTT ACA ATG ACC AAC ATG GAC CCT 324GTG GAC ACA GCC ACG TAT TAC TGT GCA CAC AGG AAC 360AGT GGC TTT GAC TAC TGG GGC CAG GGA ATC CTG GTC 396 ACC GTC TCC TCA 408179 1D7 Light Chain- ATG AGG GTC CTC GCT CAG CTC CTG GGG CTC CTG CTG 36a Variable CTC TGT TTC CCA GGT GCC AGA TGT GAC ATC CAG ATG 72 DomainACC CAG TCT CCA TCC TCA CTG TCT GCA TCT GTA GGA 108 NucleotideGAC AGA GTC ACC ATC ACT TGT CGG GCG AGT CAG GGT 144 SequenceTTT AGC AGC TGG TTA GCC TGG TAT CAG CAG AAA CCA 180GAG AAA GCC CCT AAG TCC CTG ATC TAT GCT GCA TCC 216AGT TTG CAA AGT GGG GTC CCA TCA AGG TTC AGC GGC 252AGT GGA TCT GGG ACA GAT TTC ACT CTC ACC ATC AGC 288AGC CTG CAG CCT GAA GAT TTT GCA ACT TAT TAC TGC 324CAA CAG TAT AAT AGT TAC CCT TAC ACT TTT GGC CAG 360GGG ACC AAG CTG GAG ATC AAA 381 180 1D7 Light Chain-ATG AGG GTC CTC GCT CAG CTC CTG GGG CTC CTG CTG 36 b VariableCTC TGT TTC CCA GGT GCC AGA TGT GAC ATC CAG ATG 72 DomainACC CAG TCT CCA TCC TCA CTG TCT GCA TCT GTA GGA 108 NucleotideGAC AGA GTC ACC ATC ACT TGT CGG GCG AGT CAG GGT 144 SequenceATT AGC AGC TGG TTA GCC TGG TAT CAG CAG AAA CCA 180GAG AAA GCC CCT AAG TCC CTG ATC TAT GCT GCA TCC 216AGT TTG CAA AGT GGG GTC CCA TCA AGG TTC AGC GGC 252AGT GGA TCT GGG ACA GAT TTC ACT CTC ACC ATC AGC 288AGC CTG CAG CCT GAA GAT TTT GCA ACT TAT TAC TGC 324CAA CAG TAT AAT AGT TAC CCT CTC ACT TTC GGC GGA 360GGG ACC AAG GTG GAG ATC AAA 381 181 9D5 HeavyATG GAC ACA CTT TGC TCC ACG CTC CTG CTG CTG ACC 36 Chain VariableATC CCT TCA TGG GTC TTG TCC CAG ATC ACC TTG AAG 72 DomainGAG TCT GGT CCT ACG CTG GTG AAA CCC ACA CAG ACC 108 NucleotideCTC ACG CTG ACC TGC ACC TTC TCT GGG TTC TCA CTC 144 SequenceGGC ACT AGT GGA CTG GGT GTG GGC TGG ATC CGT CAG 180CCC CCA GGA AAG GCC CTG GAG TGG CTT GCA TTC ATT 216TAT TGG GAT GAT GAT AAG CGC TAC AGC CCA TCT CTG 252AAG AGC AGG CTC ACC ATC ACC AAG GAC ACC TCC AAA 288AAC CAG GTG GTC CTT ACA ATG ACC AAC ATG GAC CCT 324GTG GAC ACA GCC ACA TAT TAC TGT GCA CAC AGA CGG 360GGC TTT TTT GAC TAC TGG GGC CAG GGA ACC CTG GTC 396 ACC GTC TCC TCA 408182 9D5 Light Chain ATG AGG GTC CTC GCT CAG CTC CTG GGG CTC CTG CTG 36Variable CTC TGT TTC CCA GGT GCC AGA TGT GAC ATC CAG ATG 72 DomainACC CAG TCT CCA TCC TCA CTG TCT GCA TCT GTA GGA 108 NucleotideGAC AGA GTC ACC ATC ACT TGT CGG GCG AGT CAG GGT 144 SequenceATT AGC AGC TGG TTA GCC TGG TAT CAG CAG AAA CCA 180GAG AAA GCC CCT AAG TCC CTG ATC TAT GCT GCA TCC 216AGT TTG CAA AGT GGG GTC CCA TCA AGG TTC AGC GGC 252AGT GGA TCT GGG ACA GAT TTC ACT CTC ACC ATC AGC 288AGC CTG CAG CCT GAA GAT TTT GCA ACT TAT TAC TGC 324CAA CAG TAT AAT AGT TAC CCG CTC ACT TTC GGC GGA 360GGG ACC AAG GTG GAG ATC AAA 381 183 ICOS.33kappaGAC ATC CAG ATG ACC CAG TCT CCA TCC TCC CTG TCT 36 NucleotideGCA TCT GTA GGA GAC AGA GTC ACC ATC ACT TGC CAG 72 SequenceGCC AGT CAG GAC ATT AGC AAT TAT TTA AGC TGG TAT 108CAG CAG AAA CCA GGG AAA GCC CCT AAG CTC CTG ATC 144TAC TAT ACA AAT CTA TTG GCA GAA GGG GTC CCA TCA 180AGG TTC AGT GGA AGT GGA TCT GGG ACA GAT TTT ACT 216TTC ACC ATC AGC AGC CTG CAG CCT GAA GAT ATT GCA 252ACA TAT TAC TGT CAA CAG TAT TAT AAC TAT CGG ACG 288TTC GGC CCT GGG ACC AAA GTG GAT ATC AAA CGT ACG 324GTG GCT GCA CCA TCT GTC TTC ATC TTC CCG CCA TCT 360GAT GAG CAG TTG AAA TCT GGA ACT GCC TCT GTT GTG 396TGC CTG CTG AAT AAC TTC TAT CCC AGA GAG GCC AAA 432GTA CAG TGG AAG GTG GAT AAC GCC CTC CAA TCG GGT 468AAC TCC CAG GAG AGT GTC ACA GAG CAG GAC AGC AAG 504GAC AGC ACC TAC AGC CTC AGC AGC ACC CTG ACG CTG 540AGC AAA GCA GAC TAC GAG AAA CAC AAA GTC TAC GCC 576TGC GAA GTC ACC CAT CAG GGC CTG AGC TCG CCC GTC 612ACA AAG AGC TTC AAC AGG GGA GAG TGT TAG 642 184 ICOS.33-g1f-GAG GTG CAG CTG GTG GAG TCT GGG GGA GGC TTG GTA 36 S267EAAG CCT GGG GGG TCC CTT AGA CTC TCC TGT GCA GCC 72 NucleotideTCT GGA TTC ACT TTC AGT GAC TAT TTC ATG CAC TGG 108 SequenceGTC CGC CAG GCT CCA GGG AAG GGG CTG GAG TGG GTT 144GGC GTC ATA GAC ACT AAA AGT TTT AAT TAT GCA ACC 180TAT TAC TCT GAT TTG GTG AAA GGC AGA TTC ACC ATC 216TCA AGA GAT GAT TCA AAA AAC ACG CTG TAT CTG CAA 252ATG AAC AGC CTG AAA ACC GAG GAC ACA GCC GTG TAT 288TAC TGT ACC GCA ACC ATC GCT GTC CCA TAT TAC TTC 324GAT TAC TGG GGC CAG GGA ACC CTG GTC ACC GTC TCC 360TCA GCT AGC ACC AAG GGC CCA TCG GTC TTC CCC CTG 396GCA CCC TCC TCC AAG AGC ACC TCT GGG GGC ACA GCG 432GCC CTG GGC TGC CTG GTC AAG GAC TAC TTC CCC GAA 468CCG GTG ACG GTG TCG TGG AAC TCA GGC GCC CTG ACC 504AGC GGC GTG CAC ACC TTC CCG GCT GTC CTA CAG TCC 540TCA GGA CTC TAC TCC CTC AGC AGC GTG GTG ACC GTG 576CCC TCC AGC AGC TTG GGC ACC CAG ACC TAC ATC TGC 612AAC GTG AAT CAC AAG CCC AGC AAC ACC AAG GTG GAC 648AAG AGA GTT GAG CCC AAA TCT TGT GAC AAA ACT CAC 684ACA TGC CCA CCG TGC CCA GCA CCT GAA CTC CTG GGG 720GGA CCG TCA GTC TTC CTC TTC CCC CCA AAA CCC AAG 756GAC ACC CTC ATG ATC TCC CGG ACC CCT GAG GTC ACA 792TGC GTG GTG GTG GAC GTG GAG CAC GAA GAC CCT GAG 828GTC AAG TTC AAC TGG TAC GTG GAC GGC GTG GAG GTG 864CAT AAT GCC AAG ACA AAG CCG CGG GAG GAG CAG TAC 900AAC AGC ACG TAC CGT GTG GTC AGC GTC CTC ACC GTC 936CTG CAC CAG GAC TGG CTG AAT GGC AAG GAG TAC AAG 972TGC AAG GTC TCC AAC AAA GCC CTC CCA GCC CCC ATC 1008GAG AAA ACC ATC TCC AAA GCC AAA GGG CAG CCC CGA 1044GAA CCA CAG GTG TAC ACC CTG CCC CCA TCC CGG GAG 1080GAG ATG ACC AAG AAC CAG GTC AGC CTG ACC TGC CTG 1116GTC AAA GGC TTC TAT CCC AGC GAC ATC GCC GTG GAG 1152TGG GAG AGC AAT GGG CAG CCG GAG AAC AAC TAC AAG 1188ACC ACG CCT CCC GTG CTG GAC TCC GAC GGC TCC TTC 1224TTC CTC TAT AGC AAG CTC ACC GTG GAC AAG AGC AGG 1260TGG CAG CAG GGG AAC GTC TTC TCA TGC TCC GTG ATG 1296CAT GAG GCT CTG CAC AAC CAC TAC ACG CAG AAG AGC 1332CTC TCC CTG TCC CCG GGT TGA 1353 185 IgG-2644 HeavyEVQLLESGGG LVQPGGSLRL SCEASGFIFK YYAMSWVRQA 40 Chain AminoPGKGLEWVSG ISGSGGSTYY ADSVKGRFTI SRDNSKHTLY 80 Acid SequenceLQMNSLRAED TAVYYCAKDG DFDWIHYYYG MDVWGQGTTV 120TVSSASTKGP SVFPLAPSSK STSGGTAALG CLVKDYFPEP 160VTVSWNSGAL TSGVHTFPAV LQSSGLYSLS SVVTVPSSSL 200GTQTYICNVN HKPSNTKVDK RVEPKSCDKT HTCPPCPAPE 240LLGGPSVFLF PPKPKDTLMI SRTPEVTCVV VDVSHEDPEV 280KFNWYVDGVE VHNAKTKPRE EQYNSTYRVV SVLTVLHQDW 320LNGKEYKCKV SNKALPAPIE KTISKAKGQP REPQVYTLPP 360SREEMTKNQV SLTCLVKGFY PSDIAVEWES NGQPENNYKT 400TPPVLDSDGS FFLYSKLTVD KSRWQQGNVF SCSVMHEALH 440 NHYTQKSLSL SPG 453 186IgG-2644 Heavy EVQLLESGGG LVQPGGSLRL SCEASGFIFK YYAMSWVRQA 40Chain Variable PGKGLEWVSG ISGSGGSTYY ADSVKGRFTI SRDNSKHTLY 80Domain Amino LQMNSLRAED TAVYYCAKDG DFDWIHYYYG MDVWGQGTTV 120Acid Sequence TVSS 124 187 IgG-2644 HeavyASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 Chain ConstantWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80 Domain AminoYICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGG 120 Acid SequencePSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW 160YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPG 329 188IgG-2644 Light AIQLTQSPSS LSASVGDRVT ITCRASQGIS SALAWYQQKP 40Chain Amino GKAPKLLIYD ASSLESGVPS RFSGSGSGTD FTLTISSLQP 80 Acid SequenceEDFATYYCQQ FNSYPHTFGG GTKVEIKRTV AAPSVFIFPP 120SDEQLKSGTA SVVCLLNNFY PREAKVQWKV DNALQSGNSQ 160ESVTEQDSKD STYSLSSTLT LSKADYEKHK VYACEVTHQG 200 LSSPVTKSFN RGEC 214 189IgG-2644 Light AIQLTQSPSS LSASVGDRVT ITCRASQGIS SALAWYQQKP 40Chain Variable GKAPKLLIYD ASSLESGVPS RFSGSGSGTD FTLTISSLQP 80Domain Amino EDFATYYCQQ FNSYPHTFGG GTKVEIK 107 Acid Sequence 190IgG-2644 Light RTVAAPSVFI FPPSDEQLKS GTASVVCLLN NFYPREAKVQ 40Chain Constant WKVDNALQSG NSQESVTEQD SKDSTYSLSS TLTLSKADYE 80Domain Amino KHKVYACEVT HQGLSSPVTK SFNRGEC 107 Acid Sequence 191IgG-2644 YYAMS 5 CDRH1 Amino Acid Sequence 192 IgG-2644GISGSGGSTY YADSVKG 17 CDRH2 Amino Acid Sequence 193 IgG-2644DGDFDWIHYY YGMDV 15 CDRH3 Amino Acid Sequence 194 IgG-2644 CDRL1RASQGISSAL A 11 Amino Acid Sequence 195 IgG-2644 CDRL2 DASSLES 7Amino Acid Sequence 196 IgG-2644 CDRL3 QQFNSYPHT 9 Amino Acid Sequence197 IgG-2644 Heavy GAG GTG CAG CTG TTG GAG TCT GGG GGA GGC TTG GTA 36Chain CAG CCT GGG GGG TCC CTG AGA CTC TCC TGT GAA GCC 72 NucleotideTCT GGA TTC ATC TTT AAA TAC TAT GCC ATG AGC TGG 108 SequenceGTC CGC CAG GCT CCA GGG AAG GGG CTG GAG TGG GTC 144TCA GGT ATT AGT GGT AGT GGT GGT AGC ACA TAC TAC 180GCA GAC TCC GTG AAG GGC CGG TTC ACC ATC TCC AGA 216GAC AAT TCC AAG CAC ACG CTG TAT CTG CAA ATG AAC 252AGC CTG AGA GCC GAG GAC ACG GCC GTT TAT TAC TGT 288GCG AAA GAT GGG GAT TTT GAC TGG ATC CAC TAT TAC 324TAT GGT ATG GAC GTC TGG GGC CAA GGG ACC ACG GTC 360ACC GTC TCC TCA GCG TCG ACC AAG GGC CCA TCC GTC 396TTC CCC CTG GCA CCC TCC TCC AAG AGC ACC TCT GGG 432GGC ACA GCG GCC CTG GGC TGC CTG GTC AAG GAC TAC 468TTC CCC GAA CCG GTG ACG GTG TCG TGG AAC TCA GGC 504GCC CTG ACC AGC GGC GTG CAC ACC TTC CCG GCT GTC 540CTA CAG TCC TCA GGA CTC TAC TCC CTC AGC AGC GTG 576GTG ACC GTG CCC TCC AGC AGC TTG GGC ACC CAG ACC 612TAC ATC TGC AAC GTG AAT CAC AAG CCC AGC AAC ACC 648AAG GTG GAC AAG AGA GTT GAG CCC AAA TCT TGT GAC 684AAA ACT CAC ACA TGC CCA CCG TGC CCA GCA CCT GAA 720CTC CTG GGG GGA CCG TCA GTC TTC CTC TTC CCC CCA 756AAA CCC AAG GAC ACC CTC ATG ATC TCC CGG ACC CCT 792GAG GTC ACA TGC GTG GTG GTG GAC GTG AGC CAC GAA 828GAC CCT GAG GTC AAG TTC AAC TGG TAC GTG GAC GGC 864GTG GAG GTG CAT AAT GCC AAG ACA AAG CCG CGG GAG 900GAG CAG TAC AAC AGC ACG TAC CGT GTG GTC AGC GTC 936CTC ACC GTC CTG CAC CAG GAC TGG CTG AAT GGC AAG 972GAG TAC AAG TGC AAG GTC TCC AAC AAA GCC CTC CCA 1008GCC CCC ATC GAG AAA ACC ATC TCC AAA GCC AAA GGG 1044CAG CCC CGA GAA CCA CAG GTG TAC ACC CTG CCC CCA 1080TCC CGG GAG GAG ATG ACC AAG AAC CAG GTC AGC CTG 1116ACC TGC CTG GTC AAA GGC TTC TAT CCC AGC GAC ATC 1152GCC GTG GAG TGG GAG AGC AAT GGG CAG CCG GAG AAC 1188AAC TAC AAG ACC ACG CCT CCC GTG CTG GAC TCC GAC 1224GGC TCC TTC TTC CTC TAT AGC AAG CTC ACC GTG GAC 1260AAG AGC AGG TGG CAG CAG GGG AAC GTC TTC TCA TGC 1296TCC GTG ATG CAT GAG GCT CTG CAC AAC CAC TAC ACG 1332CAG AAG AGC CTC TCC CTG TCC CCG GGT 1359 198 IgG-2644 HeavyGAG GTG CAG CTG TTG GAG TCT GGG GGA GGC TTG GTA 36 Chain VariableCAG CCT GGG GGG TCC CTG AGA CTC TCC TGT GAA GCC 72 DomainTCT GGA TTC ATC TTT AAA TAC TAT GCC ATG AGC TGG 108 NucleotideGTC CGC CAG GCT CCA GGG AAG GGG CTG GAG TGG GTC 144 SequenceTCA GGT ATT AGT GGT AGT GGT GGT AGC ACA TAC TAC 180GCA GAC TCC GTG AAG GGC CGG TTC ACC ATC TCC AGA 216GAC AAT TCC AAG CAC ACG CTG TAT CTG CAA ATG AAC 252AGC CTG AGA GCC GAG GAC ACG GCC GTT TAT TAC TGT 288GCG AAA GAT GGG GAT TTT GAC TGG ATC CAC TAT TAC 324TAT GGT ATG GAC GTC TGG GGC CAA GGG ACC ACG GTC 360 ACC GTC TCC TCA 372199 IgG-2644 Heavy GCG TCG ACC AAG GGC CCA TCC GTC TTC CCC CTG GCA 36Chain Constant CCC TCC TCC AAG AGC ACC TCT GGG GGC ACA GCG GCC 72 DomainCTG GGC TGC CTG GTC AAG GAC TAC TTC CCC GAA CCG 108 NucleotideGTG ACG GTG TCG TGG AAC TCA GGC GCC CTG ACC AGC 144 SequenceGGC GTG CAC ACC TTC CCG GCT GTC CTA CAG TCC TCA 180GGA CTC TAC TCC CTC AGC AGC GTG GTG ACC GTG CCC 216TCC AGC AGC TTG GGC ACC CAG ACC TAC ATC TGC AAC 252GTG AAT CAC AAG CCC AGC AAC ACC AAG GTG GAC AAG 288AGA GTT GAG CCC AAA TCT TGT GAC AAA ACT CAC ACA 324TGC CCA CCG TGC CCA GCA CCT GAA CTC CTG GGG GGA 360CCG TCA GTC TTC CTC TTC CCC CCA AAA CCC AAG GAC 396ACC CTC ATG ATC TCC CGG ACC CCT GAG GTC ACA TGC 432GTG GTG GTG GAC GTG AGC CAC GAA GAC CCT GAG GTC 468AAG TTC AAC TGG TAC GTG GAC GGC GTG GAG GTG CAT 504AAT GCC AAG ACA AAG CCG CGG GAG GAG CAG TAC AAC 540AGC ACG TAC CGT GTG GTC AGC GTC CTC ACC GTC CTG 576CAC CAG GAC TGG CTG AAT GGC AAG GAG TAC AAG TGC 612AAG GTC TCC AAC AAA GCC CTC CCA GCC CCC ATC GAG 648AAA ACC ATC TCC AAA GCC AAA GGG CAG CCC CGA GAA 684CCA CAG GTG TAC ACC CTG CCC CCA TCC CGG GAG GAG 720ATG ACC AAG AAC CAG GTC AGC CTG ACC TGC CTG GTC 756AAA GGC TTC TAT CCC AGC GAC ATC GCC GTG GAG TGG 792GAG AGC AAT GGG CAG CCG GAG AAC AAC TAC AAG ACC 828ACG CCT CCC GTG CTG GAC TCC GAC GGC TCC TTC TTC 864CTC TAT AGC AAG CTC ACC GTG GAC AAG AGC AGG TGG 900CAG CAG GGG AAC GTC TTC TCA TGC TCC GTG ATG CAT 936GAG GCT CTG CAC AAC CAC TAC ACG CAG AAG AGC CTC 972 TCC CTG TCC CCG GGT987 200 IgG-2644 Light GCC ATC CAG TTG ACC CAG TCT CCA TCC TCC CTG TCT36 Chain GCA TCT GTA GGA GAC AGA GTC ACC ATC ACT TGC CGG 72 NucleotideGCA AGT CAG GGC ATT AGC AGT GCT TTA GCC TGG TAT 108 SequenceCAG CAG AAA CCA GGG AAA GCT CCT AAG CTC CTG ATC 144TAT GAT GCC TCC AGT TTG GAA AGT GGG GTC CCA TCA 180AGG TTC AGC GGC AGT GGA TCT GGG ACA GAT TTC ACT 216CTC ACC ATC AGC AGC CTG CAG CCT GAA GAT TTT GCA 252ACT TAT TAC TGT CAA CAG TTT AAT AGT TAC CCT CAC 288ACT TTC GGC GGA GGG ACC AAG GTG GAG ATC AAA CGT 324ACG GTG GCT GCA CCA TCT GTC TTC ATC TTC CCG CCA 360TCT GAT GAG CAG TTG AAA TCT GGA ACT GCC TCT GTT 396GTG TGC CTG CTG AAT AAC TTC TAT CCC AGA GAG GCC 432AAA GTA CAG TGG AAG GTG GAT AAC GCC CTC CAA TCG 468GGT AAC TCC CAG GAG AGT GTC ACA GAG CAG GAC AGC 504AAG GAC AGC ACC TAC AGC CTC AGC AGC ACC CTG ACG 540CTG AGC AAA GCA GAC TAC GAG AAA CAC AAA GTC TAC 576GCC TGC GAA GTC ACC CAT CAG GGC CTG AGC TCG CCC 612GTC ACA AAG AGC TTC AAC AGG GGA GAG TGT 642 201 IgG-2644 LightGCC ATC CAG TTG ACC CAG TCT CCA TCC TCC CTG TCT 36 Chain VariableGCA TCT GTA GGA GAC AGA GTC ACC ATC ACT TGC CGG 72 DomainGCA AGT CAG GGC ATT AGC AGT GCT TTA GCC TGG TAT 108 NucleotideCAG CAG AAA CCA GGG AAA GCT CCT AAG CTC CTG ATC 144 SequenceTAT GAT GCC TCC AGT TTG GAA AGT GGG GTC CCA TCA 180AGG TTC AGC GGC AGT GGA TCT GGG ACA GAT TTC ACT 216CTC ACC ATC AGC AGC CTG CAG CCT GAA GAT TTT GCA 252ACT TAT TAC TGT CAA CAG TTT AAT AGT TAC CCT CAC 288ACT TTC GGC GGA GGG ACC AAG GTG GAG ATC AAA 321 202 IgG-2644 LightCGT ACG GTG GCT GCA CCA TCT GTC TTC ATC TTC CCG 36 Chain ConstantCCA TCT GAT GAG CAG TTG AAA TCT GGA ACT GCC TCT 72 DomainGTT GTG TGC CTG CTG AAT AAC TTC TAT CCC AGA GAG 108 NucleotideGCC AAA GTA CAG TGG AAG GTG GAT AAC GCC CTC CAA 144 SequenceTCG GGT AAC TCC CAG GAG AGT GTC ACA GAG CAG GAC 180AGC AAG GAC AGC ACC TAC AGC CTC AGC AGC ACC CTG 216ACG CTG AGC AAA GCA GAC TAC GAG AAA CAC AAA GTC 252TAC GCC TGC GAA GTC ACC CAT CAG GGC CTG AGC TCG 288CCC GTC ACA AAG AGC TTC AAC AGG GGA GAG TGT 321 203 ICOS.4 EpitopeSIFDPPPFKV TL 12 Amino Acid Sequence 204 huIgG1f HeavyASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 Chain ConstantWNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80 Domain with C-YICNVNHKPS NTKVDKRVEP KSCDKTHTCP PCPAPELLGG 120 terminal lysinePSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW 160YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSREE 240MTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPGK 330 205Isoform 2 MKSGLWYFFL FCLRIKVLTG EINGSANYEM FIFHNGGVQI 40 (Q9Y6W8-2)LCKYPDIVQQ FKMQLLKGGQ ILCDLTKTKG SGNTVSIKSL 80KFCHSQLSNN SVSFFLYNLD HSHANYYFCN LSIFDPPPFK 120VTLTGGYLHI YESQLCCQLK FWLPIGCAAF VVVCILGCIL 160 ICWLTKKM 168 206Human IgG1 ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS 40 (P01857-1)WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT 80YICNVNHKPS NTKVDKKVEP KSCDKTHTCP PCPAPELLGG 120PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW 160YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK 200EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSRDE 240LTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV 280LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT 320 QKSLSLSPGK 330 207VKI O18 DIQMTQSPSS LSASVGDRVT ITCQASQDIS NYLNWYQQKP 40GKAPKLLIYD ASNLETGVPS RFSGSGSGTD FTFTISSLQP 80 EDIATYYCQQ YDNLP 95 208JK3 FTFGPGTKVD IK 12 209 VH3-15EVQLVESGGG LVKPGGSLRL SCAASGFTFS NAWMSWVRQA 40PGKGLEWVGR IKSKTDGGTT DYAAPVKGRF TISRDDSKNT 80 LYLQMNSLKT EDTAVYYCTT 100210 JH4 YFDYWGQGTL VTVSS 15 211 mICOS.1-mG1EVDLVETGGG LVQPGGSLKL SCVASGFTFS RYWMFWIRQA 40 Heavy ChainPGKGLEWVSS VSTDGRSTYY PDSVQGRFTI SRNDAENTVY 80LQMNSLRSED TATYYCAKEG YYDGSYYAYY FDYWGQGVTV 120TVSSAKTTPP SVYPLAPGSA AQTNSMVTLG CLVKGYFPEP 160VTVTWNSGSL SSGVHTFPAV LQSDLYTLSS SVTVPSSTWP 200SETVTCNVAH PASSTKVDKK IVPRDCGCKP CICTVPEVSS 240VFIFPPKPKD VLTITLTPKV TCVVVDISKD DPEVQFSWFV 280DDVEVHTAQT QPREEQFNST FRSVSELPIM HQDWLNGKEF 320KCRVNSAAFP APIEKTISKT KGRPKAPQVY TIPPPKEQMA 360KDKVSLTCMI TDFFPEDITV EWQWNGQPAE NYKNTQPIMD 400TDGSYFVYSK LNVQKSNWEA GNTFTCSVLH EGLHNHHTEK 440 SLSHSPGK 448 212mICOS.1-mG1 DVQMAQSPSS LAASPGESVS INCKASKSIS KYLAWYQQKP 40 Light ChainGKANKLLIYS GSTLQSGTPS RFSGSGSGTD FTLTIRNLEP 80EDFGLYYCQQ HNAYPPTFGT GTKLELKRAD AAPTVSIFPP 120SSEQLTSGGA SVVCFLNNFY PKDINVKWKI DGSERQNGVL 160NSWTDQDSKD STYSMSSTLT LTKDEYERHN SYTCEATHKT 200 STSPIVKSFN RNEC 214 213ICOS.4-mG1 EVQLVESGGG LVKPAGSLTL SCVASGFTFS DYFMHWVRQA 40 Heavy ChainPGKGLEWVAV IDTKSFNYAT YYSDLVKGRF TVSRDDSQGM 80VYLQMNNLRK EDTATYYCTA TIAVPYYFDY WGQGTMVTVS 120SAKTTPPSVY PLAPGSAAQT NSMVTLGCLV KGYFPEPVTV 160TWNSGSLSSG VHTFPAVLQS DLYTLSSSVT VPSSTWPSET 200VTCNVAHPAS STKVDKKIVP RDCGCKPCIC TVPEVSSVFI 240FPPKPKDVLT ITLTPKVTCV VVDISKDDPE VQFSWFVDDV 280EVHTAQTQPR EEQFNSTFRS VSELPIMHQD WLNGKEFKCR 320VNSAAFPAPI EKTISKTKGR PKAPQVYTIP PPKEQMAKDK 360VSLTCMITDF FPEDITVEWQ WNGQPAENYK NTQPIMDTDG 400SYFVYSKLNV QKSNWEAGNT FTCSVLHEGL HNHHTEKSLS 440 HSPGK 445 214 ICOS.4-mG1DIQMTQSPSS LPASLGDRVT INCQASQDIS NYLSWYQQKP 40 Light ChainGKAPKLLIYY TNLLADGVPS RFSGSGSGRD YSFTISSLES 80EDIGSYYCQQ YYNYRTFGPG TKLEIKRADA APTVSIFPPS 120SEQLTSGGAS VVCFLNNFYP KDINVKWKID GSERQNGVLN 160SWTDQDSKDS TYSMSSTLTL TKDEYERHNS YTCEATHKTS 200 TSPIVKSFNR NEC 213 215ICOS.34-G1f EVQLVESGGG LVKPGGSLRL SCAASGFTFS DYFMHWVRQA 40 Heavy ChainPGKGLEWVGV IDTKSFNYAT YYSDLVKGRF TISRDDSKNT 80LYLQMNSLKT EDTAVYYCTT TIAVPYYFDY WGQGTLVTVS 120SASTKGPSVF PLAPSSKSTS GGTAALGCLV KDYFPEPVTV 160SWNSGALTSG VHTFPAVLQS SGLYSLSSVV TVPSSSLGTQ 200TYICNVNHKP SNTKVDKRVE PKSCDKTHTC PPCPAPELLG 240GPSVFLFPPK PKDTLMISRT PEVTCVVVDV SHEDPEVKFN 280WYVDGVEVHN AKTKPREEQY NSTYRVVSVL TVLHQDWLNG 320KEYKCKVSNK ALPAPIEKTI SKAKGQPREP QVYTLPPSRE 360EMTKNQVSLT CLVKGFYPSD IAVEWESNGQ PENNYKTTPP 400VLDSDGSFFL YSKLTVDKSR WQQGNVFSCS VMHEALHNHY 440 TQKSLSLSPG 450 216ICOS.34-G1f DIQMTQSPSS LSASVGDRVT ITCQASQDIS NYLSWYQQKP 40 Light ChainGKAPKLLIYY TNLLADGVPS RFSGSGSGTD FTFTISSLQP 80EDIATYYCQQ YYNYRTFGPG TKVDIKRTVA APSVFIFPPS 120DEQLKSGTAS VVCLLNNFYP REAKVQWKVD NALQSGNSQE 160SVTEQDSKDS TYSLSSTLTL SKADYEKHKV YACEVTHQGL 200 SSPVTKSFNR GEC 213 217ICOS.35-G1f EVQLVESGGG LVKPGGSLRL SCAASGFTFS DYFMHWVRQA 40 Heavy ChainPGKGLEWVGV IDTKSFNYAT YYSDLVKGRF TISRDDSKNT 80LYLQMNSLKT EDTAVYYCTA TIAVPYYFDY WGQGTLVTVS 120SASTKGPSVF PLAPSSKSTS GGTAALGCLV KDYFPEPVTV 160SWNSGALTSG VHTFPAVLQS SGLYSLSSVV TVPSSSLGTQ 200TYICNVNHKP SNTKVDKRVE PKSCDKTHTC PPCPAPELLG 240GPSVFLFPPK PKDTLMISRT PEVTCVVVDV SHEDPEVKFN 280WYVDGVEVHN AKTKPREEQY NSTYRVVSVL TVLHQDWLNG 320KEYKCKVSNK ALPAPIEKTI SKAKGQPREP QVYTLPPSRE 360EMTKNQVSLT CLVKGFYPSD IAVEWESNGQ PENNYKTTPP 400VLDSDGSFFL YSKLTVDKSR WQQGNVFSCS VMHEALHNHY 440 TQKSLSLSPG 450 218ICOS.35-G1f DIQMTQSPSS LSASVGDRVT ITCQASQDIS NYLSWYQQKP 40 Light ChainGKAPKLLIYY TNLLADGVPS RFSGSGSGTD FTFTISSLQP 80EDIATYYCQQ YYNYRTFGPG TKVDIKRTVA APSVFIFPPS 120DEQLKSGTAS VVCLLNNFYP REAKVQWKVD NALQSGNSQE 160SVTEQDSKDS TYSLSSTLTL SKADYEKHKV YACEVTHQGL 200 SSPVTKSFNR GEC 213 219NKTR-214 PTSSSTKKTQ LQLEHLLLDL QMILNGINNY KNPKLTRMLT 40 IL-2 pathwayFKFYMPKKAT ELKHLQCLEE ELKPLEEVLN LAQSKNFHLR 80 agonistPRDLISNINV IVLELKGSET TFMCEYADET ATIVEFLNRW 120 ITFSQSIIST LT 132

We claim:
 1. A method for treating or delaying progression of cancer ina human subject comprising administering to the human subject aneffective amount of an antibody that binds to human InducibleCOStimulator molecule (ICOS), wherein the antibody comprises a heavychain variable domain comprising CDR1, CDR2, and CDR3 regions comprisingthe amino acid sequences of SEQ ID NOs: 9, 10 and 11, respectively, anda light chain variable domain comprising CDR1, CDR2, and CDR3 regionscomprising the amino acid sequences of SEQ ID NOs: 12, 14 and 15,respectively.
 2. The method of claim 1, wherein the antibody comprisesheavy and light chain variable regions comprising the amino acidsequences of SEQ ID NOs: 5 and 6, respectively.
 3. The method of claim1, wherein the cancer is bladder cancer, breast cancer, uterine/cervicalcancer, ovarian cancer, prostate cancer, testicular cancer, esophagealcancer, gastrointestinal cancer, pancreatic cancer, colon cancer, kidneycancer, head and neck cancer, lung cancer, stomach cancer, germ cellcancer, bone cancer, liver cancer, thyroid cancer, skin cancer, neoplasmof the central nervous system, lymphoma, leukemia, myeloma, sarcoma, orvirus-related cancer.
 4. The method of claim 1, wherein the cancer iscolorectal cancer (CRC), head and neck squamous cell carcinoma (HNSCC),melanoma, NSCLC-adenocarcinoma type (NSCLC-AD), NSCLC-squamous cell type(NSCLC-SQC), adenocarcinoma of the prostate (PRC), renal cell carcinoma(RCC), or urothelial carcinoma (UCC).
 5. The method of claim 1, furthercomprising administering one or more additional therapeutic agent(s) tothe human subject.
 6. The method of claim 5, wherein the additionaltherapeutic agent(s) is a chemotherapeutic agent.
 7. The method of claim5, wherein the additional therapeutic agent(s) is an anti-programmeddeath protein 1 (PD-1) antibody, an anti-programmed death ligand 1(PD-L1) antibody, and/or an anti-cytotoxic T-lymphocyte-associatedprotein 4 (CTLA-4) antibody.
 8. The method of claim 1, wherein themethod comprises at least one administration cycle, wherein for each ofthe at least one administration cycle, at least one dose of the antibodyis administered at a dose of about 375 mg.
 9. The method of claim 8,wherein the antibody is administered in an amount or frequencysufficient to achieve and/or maintain a receptor occupancy of less thanabout 80%.
 10. A method of stimulating an immune response in a humansubject comprising administering to the human subject an effectiveamount of an antibody that binds to human ICOS, wherein the antibodycomprises a heavy chain variable domain comprising CDR1, CDR2, and CDR3regions comprising the amino acid sequences of SEQ ID NOs: 9, 10 and 11,respectively, and a light chain variable domain comprising CDR1, CDR2,and CDR3 regions comprising the amino acid sequences of SEQ ID NOs: 12,14 and 15, respectively.
 11. The method of claim 10, wherein theantibody comprises heavy and light chain variable regions comprising theamino acid sequences of SEQ ID NOs: 5 and 6, respectively.
 12. Themethod of claim 10, wherein the subject has a tumor and an immuneresponse against the tumor is stimulated.
 13. The method of claim 10,wherein the subject has a chronic viral infection and an immune responseagainst the viral infection is stimulated.
 14. A method for treating ordelaying progression of cancer in a human subject comprisingadministering to the human subject an effective amount of a humanizedantibody that binds to human ICOS, wherein the antibody comprises aheavy chain variable region comprising an amino acid sequence at least85% identical to SEQ ID NO: 5 or a light chain variable regioncomprising an amino acid sequence at least 85% identical to SEQ ID NO:6.
 15. The method of claim 14, wherein the antibody comprises a heavychain variable region comprising an amino acid sequence at least 90%identical to SEQ ID NO: 5 or a light chain variable region comprising anamino acid sequence at least 90% identical to SEQ ID NO:
 6. 16. Themethod of claim 14, wherein the antibody comprises a heavy chainvariable region comprising an amino acid sequence at least 95% identicalto SEQ ID NO: 5 or a light chain variable region comprising an aminoacid sequence at least 95% identical to SEQ ID NO:
 6. 17. The method ofclaim 14, wherein the cancer is bladder cancer, breast cancer,uterine/cervical cancer, ovarian cancer, prostate cancer, testicularcancer, esophageal cancer, gastrointestinal cancer, pancreatic cancer,colon cancer, kidney cancer, head and neck cancer, lung cancer, stomachcancer, germ cell cancer, bone cancer, liver cancer, thyroid cancer,skin cancer, neoplasm of the central nervous system, lymphoma, leukemia,myeloma, sarcoma, or virus-related cancer.
 18. The method of claim 14,further comprising administering one or more additional therapeuticagent(s) to the human subject.
 19. The method of claim 18, wherein theadditional therapeutic agent(s) is an anti-programmed death protein 1(PD-1) antibody, an anti-programmed death ligand 1 (PD-L1) antibody,and/or an anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4)antibody.
 20. The method of claim 14, wherein the method comprises atleast one administration cycle, wherein for each of the at least oneadministration cycle, at least one dose of the antibody is administeredat a dose of about 375 mg.